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The Journal of Immunology, 2003, 170: 4095-4101.
Copyright © 2003 by The American Association of Immunologists

The gp49B1 Inhibitory Receptor Regulates the IFN-{gamma} Responses of T Cells and NK Cells

Xiaogang Gu*, Amale Laouar*, Junmei Wan*, Massoud Daheshia{dagger},{ddagger}, Judy Lieberman*, Wayne M. Yokoyama§, Howard R. Katz{dagger},{ddagger} and N. Manjunath1,*

* Center for Blood Research and {dagger} Department of Medicine, Harvard Medical School, Boston, MA 02115; {ddagger} Division of Rheumatology, Immunology and Allegry, Brigham and Women’s Hospital, Boston, MA 02115; and § Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
The magnitude and diversity of Ag-specific T cell effector activity have been proposed to be controlled by an integration of positive signals transduced by the TCR and negative signals originating from inhibitory cell surface molecules. Although the lectin family of NK cell-associated inhibitory receptors has been reported to regulate the function of murine CTLs, gp49B1, the Ig superfamily member is not known to be expressed on T cells. Moreover, the consequences of the lack of an endogenously expressed NK cell-associated inhibitory receptor on T cell functions are not known. We report that gp49B1 is expressed by nearly all activated CD8 and CD4 T cells in addition to NK cells during an immune response to viral, bacterial, or tumor challenge. Kinetics of gp49B1 expression parallel functional capability and subside in the memory phase. Following vaccinia viral infection, IFN-{gamma} production by both subsets of T cells and NK cells is enhanced in gp49B1-deficient mice compared with gp49B1+/+ mice. The stimulation threshold for IFN-{gamma} production is also lower in gp49B1-deficient T cells. In contrast, no significant differences were observed in the cytotoxic responses. We conclude that gp49B1 is a unique inhibitory receptor that is induced in multiple lineages of innate and adaptive immune cells during an infection and controls their IFN-{gamma}, but not cytotoxic responses.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Signaling through the TCR initiates a cascade of phosphorylation events that leads to T cell activation. Until recently, the strength of the TCR and costimulatory signals was considered to be the major regulator of T cell activity. However, NK cell-associated inhibitory receptors (NK-IRs)2 that recruit phosphatases to their cytoplasmic immunoreceptor tyrosine-based inhibitory motifs (ITIMs) also influence CD8 T cell function (reviewed in Ref.1). Two classes of NK-IRs exist in humans and mice: type I membrane proteins that belong to the Ig superfamily, such as the killer cell Ig-like receptors (KIRs) and leukocyte Ig-like receptors/Ig-like transcripts/leukocyte-associated Ig-like receptors in humans, and gp49B1 in mice; and type II membrane proteins that have homology to C-type lectins, such as the CD94/NKG2 receptors in humans and mice and the Ly49 receptors in mice (2).

A number of studies have shown that KIRs are expressed by memory/effector CTL under conditions of chronic Ag stimulation, such as tumors and HIV infection, leading to the view that the NK-IRs perhaps serve to reduce CTL-mediated immunopathology after protracted antigenic stimulation (3, 4, 5, 6, 7, 8, 9, 10, 11, 12). Although these studies authenticate that CTL can express NK-IRs under certain situations, their role in a primary immune response in vivo was not clear. Recently, using a polyoma infection model in mice, Moser et al. (13) demonstrated that the NK-IR, CD94-NKG2A, down-regulates the CTL response during viral clearance and virus-induced oncogenesis. Other studies in mice also suggest that several NK-IRs can be expressed during acute viral infection, but some reports have questioned the role of such receptors (14, 15, 16, 17).

Two related transmembrane members of the gp49 family, gp49A and gp49B1, are expressed constitutively in mast cells and are induced in NK cells after murine CMV infection (18, 19, 20). Although highly homologous to gp49B1 (88% overall amino acid identity), gp49A has a much shorter cytoplasmic domain, lacks the two ITIMs present in gp49B1, and activates mast cells when cross-linked by Ab (18, 19, 21). gp49B1 inhibits mast cell activation in vitro by recruiting Src homology protein-1 when co-cross-linked with Fc{epsilon}RI (22). Moreover, mast cells in gp49B1-deficient mice exhibit increased sensitivity to Fc{epsilon}RI-dependent mast cell activation that leads to greater tissue inflammation (23). gp49B1 also inhibits NK1.1-mediated cytokine release from NK cells when co-cross-linked with the stimulatory NK1.1 mAb (20). Whereas the lectin-like CD94-NKG2 and LY49 receptors have been reported to be expressed by CTL in mice, expression of gp49 in T cells remains unexplored.

We have previously reported that distinct populations of effector and memory CTL can be generated from Ag-primed CD8 T cells in vitro by varying the cytokine milieu (24). We further found by gene chip analysis, that gp49A/B1 is one of the genes expressed selectively in effector CTL (our unpublished data). Therefore, we have defined the expression of gp49A/B1 in effector T cells and determined its function by comparing normal and gp49B1-deficient mice. We found that gp49B1 is expressed in effector cells of both the CD4 and CD8 T cell lineages and serves to selectively control cytokine secretion function.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Mice

P14 TCR Tg mice (25), expressing the transgenic TCR specific for the lymphocytic choriomeningitis virus (LCMV) gp33–41 peptide in the C57BL/6 background were the kind gift of Dr. R. Ahmed (Emory University, Atlanta, GA). Male gp49B1-/- mice (23) backcrossed into the C57BL/6 background for six generations and their gp49+/+ littermate controls bred in parallel, were used at 6–10 wk of age for the experiments. C57BL/6 mice were purchased from The Jackson Laboratory (Bar Harbor, ME). Mice were maintained under viral Ag-free/specific pathogen-free conditions in microisolator cages.

Peptide stimulation

To generate effector CTL in vitro, splenocytes from P14 mice were stimulated with 5 µg/ml gp33–41 peptide, KAVYNFATC (synthesized at BioSource International, Camarillo, CA) and cultured in 20 ng/ml IL-2 for 7 days as described previously (24). After 7 days of culture, >95% of viable cells are CD8 T cells (24).

Viral, bacterial, and allogeneic tumor challenge

gp49B1-deficient mice and their littermate controls, backcrossed (N6) to C57BL/6 background, were infected by i.p. injection with either the WR strain of vaccinia virus (106 PFU/mouse in 200 µl PBS), 104 CFU of Listeria monocytogenes (LM), or 5 x 106 mastocytoma cell line, P815 (H-2d), and at indicated times postinfection, their peritoneal exudate lymphocytes (PEL), spleen, and ovaries were harvested.

Flow cytometry

For phenotypic analyses, splenocytes from P14 TCR Tg mice and PEL and splenocytes from normal and gp49B1-deficient mice were stained with anti-mouse CD8-Cy5, CD4-FITC, and PE-labeled Abs to mouse CD62L, CD69, CD44, CD25, or CD43 (1B11) (BD PharMingen, San Diego, CA). All samples were analyzed on a FACScan flow cytometer (BD Biosciences, Mountain View, CA). gp49A/B1 expression was measured using the hamster IgG monoclonal, H1.1, that recognizes both gp49A and gp49B1 (20), followed by biotin-labeled goat anti-hamster Ig and streptavidin-PE. To test gp49A- and gp49B1-specific expression, cells were stained with either the rat IgM monoclonal B23.1 (26), specific for gp49B1, followed by FITC-labeled goat anti-rat IgM, or with the rabbit polyclonal Ab raised against the gp49A201–216 peptide (19) followed by FITC-labeled anti-rabbit IgG. Isotype controls included syrian hamster IgG, rat IgM, and rabbit IgG Abs (Jackson ImmunoResearch Laboratories, West Grove, PA).

Intracellular IFN-{gamma}, cytotoxicity, and lymphocyte proliferation assays

These assays have been described previously (24). Briefly, to detect IFN-{gamma} production, 0.5 x 106 peptide-stimulated P14 splenocytes or PEL from vaccinia-infected mice were stimulated with either gp33–41 peptide-pulsed EL-4 cells or vaccinia virus-infected (10 PFU/cell, overnight) adherent macrophages from wild-type C57BL/6 mice (elicited 3 days after ip injection of 1% thioglycolate broth), or anti-CD3 (at indicated concentrations) in the presence of 1 µM Golgi stop. Non-peptide-pulsed and uninfected EL-4 cells served as controls. After 6–8 h of incubation, the cells were stained with Cy5-labeled anti-CD8, FITC-labeled anti-CD4, or FITC-labeled NK1.1 Ab (BD PharMingen); fixed; permeabilized; and stained with PE-labeled anti-mouse IFN-{gamma} Ab.

Peptide stimulated P14 T cells were tested for lysis of 51Cr-labeled EL-4 (H-2b) target cells unpulsed or pulsed with 10 µg/ml gp33–41 peptide in a 4-h chromium release assay. To test anti-viral cytotoxicity, 51Cr-labeled, uninfected or vaccinia virus-infected (10 PFU/cell, overnight) EL-4 cells were used at targets. Background cytotoxicity of non-peptide-pulsed EL-4 cells or uninfected EL-4 cells (always <5%) was subtracted to calculate peptide and viral-specific cytotoxicity. NK cell cytotoxicity was similarly tested using 51Cr-labeled Yac-1 cells.

RT-PCR

RT-PCR was performed on RNA extracted from peptide stimulated P14 splenocytes using gp49A and gp49B1-specific upstream primers and the common downstream primer as described earlier (19).

Measurement of virus titers

Ovaries were harvested from vaccinia-infected mice and homogenized. Viral titers were determined by serial 10-fold dilutions using CV-1 cells as described (27).


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
gp49B1 is induced in Ag-specific CD8 T cells coordinately with development of effector functions

CD8 T cells from P14 mice express a transgenic TCR specific for the LCMV glycoprotein epitope, gp33–41 (25). When stimulated with the cognate peptide and cultured in the presence of 20 ng/ml rIL-2, the Tg CD8 T cells differentiate over 4–6 days into cells that exhibit all features of effector CTL, including the effector-specific phenotype and high levels of cytotoxicity (24). We used this system to study the kinetics of gp49A/B1 expression vis-à-vis the development of effector functions. Peptide stimulated P14 splenocytes were tested every 2 days until 10 days poststimulation for the binding of mAb H1.1 that recognizes both gp49A and gp49B1 (20). The cells were also tested in parallel for peptide-specific cytotoxicity and IFN-{gamma} production. As Fig. 1 shows, unstimulated naive CD8 T cells were uniformly negative for gp49A/B1 expression and did not exhibit cytotoxicity or produce IFN-{gamma}. gp49A/B1 expression progressively increased after peptide stimulation and nearly all CD8 T cells expressed high levels of gp49A/B1 6–8 days after stimulation. The increasing levels of gp49A/B1 expression paralleled the progressive increase in Ag-specific IFN-{gamma} producing and cytotoxic functions, suggesting that gp49A/B1 may be specifically expressed by CD8 T cells with capacity for immediate effector functions. We have recently reported that while IL-2 progressively promotes the development of effector phenotype and functions in Ag-stimulated CD8 T cells, IL-15 tends to reverse the process (24). Thus, to test whether gp49A/B1 expression also decreases in IL-15-treated cells, we treated day 5 IL-2-differentiated effector cells with IL-15 for 5 days and tested them along with cells continually maintained in IL-2 for effector functions. While gp49A/B1 expression progressively increased in cells maintained continuously in IL-2 (Fig. 1, day 10), gp49A/B1 expression and effector functions did not increase in IL-15 treated cells (Fig. 1, filled bars). Compared with cells continually maintained in IL-2, the IL-15-switched cells showed dramatically reduced mean fluorescent intensity (MFI) for both IFN-{gamma} and gp49A/B1 staining (there was also an ~20% reduction in the number of positive cells).



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  		FIGURE 1. gp49A/B1 expression parallels the functional capability of CTL. Splenocytes from P14 TCR Tg mice were stimulated with gp33–41 peptide and cultured in IL-2 for 10 days. A portion of cells from the day 5 culture was switched to IL-15 and cultured for 5 more days. At indicated time points, the cells were stained with anti-CD8 and gp49A/B1 mAb H1.1, and analyzed by flow cytometry. In parallel, the cells were tested for peptide-specific IFN-{gamma} production by intracellular staining and for specific lysis of peptide-pulsed EL-4 targets in a 4-h chromium release assay. Representative overlay histograms of gp49A/B1 and IFN-{gamma} staining of unstimulated (naive) or day 6 peptide-stimulated (activated), CD8-gated cells are shown in the top panel. The open histograms in the overlay represent isotype control Ab staining. The bar graphs in the middle panel show the kinetics of gp49A/B1 expression, IFN-{gamma} production, and cytotoxicity of cells cultured in IL-2 (open bars) or cells switched to IL-15 (filled bars) as MFI or percentage of specific cytotoxicity. All values represent mean ± SD of two experiments. CD8 T cell numbers (determined by flow cytometry) were equalized at each time point to calculate the E:T ratio in the cytotoxicity assays. Cytotoxicity results are shown at an E:T ratio of 6:1. Similar differences were seen at three other ratios tested (not shown). The bottom panel shows gp49A-and B1-specific expression 8 days after peptide stimulation. The open histograms in the overlay represent staining with isotype controls.

 
Because gp49A is a stimulatory receptor and gp49B1 is an inhibitory receptor, we also stained the cells on poststimulation day 8 (when they had high levels of gp49A/B1) with a rabbit polyclonal Ab that is gp49A-specific and the rat monoclonal, B23.1, which is gp49B1-specific (20, 26). Specific binding was seen with gp49B1-specific Ab (Fig. 1, bottom panel). The staining intensity of gp49B1-specific monoclonal, B23.1 is lower compared with gp49A/B1-specific H1.1 monoclonal probably because, a two-step staining procedure (with FITC-labeled second step reagent) was used for B23.1 whereas a three-step staining (with streptavidin PE as a third step reagent) was used for H1.1. However, no staining above isotype control was seen with gp49A-specific Ab. Thus, the inhibitory gp49B1, but not the stimulatory gp49A is expressed by effector CD8 T cells. These results were also confirmed by RT-PCR using gp49A- and gp49B1-specific primers (data not shown). Collectively, these results suggest that gp49 B1 expression closely parallels effector potential, raising the possibility that gp49 B1 may regulate effector responses.

gp49B1 is expressed by both CD8 and CD4 effector T cells in vivo, and its expression subsides in memory cells

To test whether gp49B1 is also expressed in an effector-specific manner in vivo, we tested naive, effector, and memory T cells aftervaccinia infection. We have previously reported that T cells accumulating in the peritoneal cavity 7 days after i.p. infection with vaccinia virus are highly enriched for effector T cells (28). Thus, to determine whether gp49A/B1 is induced in Ag-specific T cells after infection, we compared naive T cells from uninfected mice, T cells accumulating in the PEL, as well as the splenic T cells harvested 7 days after infection, for effector phenotype and gp49A/B1 expression. It has previously been shown that the isoform of CD43 recognized by the mAb, 1B11 is specifically expressed by Ag-specific effector T cells, but not by naive or memory T cells (29). Because MHC-peptide tetramers are not available for vaccinia virus, we used CD62L and 1B11 staining to identify Ag-specific T cells. Naive T cells in the spleen from uninfected mice uniformly expressed CD62-L, but did not express gp49A/B1 or the 1B11 epitope. In infected mice, over 90% of T cells in PEL and ~50% T cells in the spleen down-regulated L-selectin and up-regulated the expression of the 1B11 epitope of CD43. A corresponding percentage of T cells in the PEL and spleen alsoexpressed high levels of gp49A/B1 (Fig. 2), suggesting that gp49A/B1 is expressed selectively in effector T cells. Similar to in vitro generated CTL, gp49A/B1 expression as well as L-selectin down regulation and 1B11 up-regulation progressively increased between days 4–8 after infection (data not shown).



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  		FIGURE 2. Effector cells, but not naive and memory cells, express gp49A/B1 in vivo. Splenocytes from uninfected mice (Naive), splenocytes and PEL from mice infected with vaccinia virus for 7 days (Effector), and splenocytes from mice that were infected with vaccinia virus 2 mo earlier (Memory) were stained with anti-CD8, anti-CD4, and gp49A/B1 mAb, H1.1, and analyzed by flow cytometry. Overlay histograms of H1.1 mAb staining (filled histograms) and hamster IgG isotype control staining (open histograms) are shown for CD8- and CD4-gated cells. In the memory panel, the cells were also gated for high level expression of CD44 (R2). Naive and effector cells were also stained with anti-L-selectin mAb and the CD43 mAb, 1B11 and the corresponding histograms display an overlay of effector (filled) and naive (open) cell staining. Results are representative of five experiments.

 
It has been reported that the CD94-NKG2 receptor is expressed for long periods after Ag stimulation (13). Thus, we tested whether long-term memory T cells generated in vivo retain gp49A/B1 expression. To generate memory T cells, we infected C57BL/6 mice with vaccinia virus, rested them for 10 wk, and stained them with CD44 and H1.1 mAbs. Compared with uninfected mice, splenocytes from infected mice had higher levels of CD44high T cells (36 ± 5% vs 20 ± 7%, n = 4), suggesting that the expansion was because of memory cells generated as a consequence of vaccinia infection. The CD44high CD4 and CD8 T cells expressed barely detectable levels of gp49A/B1 (Fig. 2). The splenocytes from these mice did not exhibit detectable anti-vaccinia cytotoxicity although they were capable of viral-specific proliferation in vitro (data not shown). Collectively our results suggest that gp49A/B1 expression parallels the rise in functional capability and decreases in memory T cells.

To determine whether gp49A and/or gp49B1 is up-regulated in vivo, we stained PEL from gp49B1+/+ and gp49B1-/- mice harvested 7 days after vaccinia infection with H1.1 mAb, gp49A-specific, and gp49B1-specific Abs (20, 26). CD8 T cells from gp49B1+/+ mice stained with the H1.1 and gp49B1-specific Ab, but exhibited no staining with gp49A-specific Ab (Fig. 3). In contrast, CD8 T cells from gp49B1-deficient mice did not stain with any of the Abs. Similar results were also obtained with CD4 T cells (data not shown).



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  		FIGURE 3. gp49B1, but not gp49A, is expressed on activated T cells. PELs from vaccinia-infected gp49+/+ (wild type (WT)) and gp49B1-deficient mice (knockout (KO)) harvested on day 7 postinfection were stained with anti-CD8 and the hamster mAb H1.1 (recognizes both gp49A and gp49B1), or rabbit anti-gp49A201–216 polyclonal (specific for gp49A) or the rat mAb B23.1 (specific for gp49B1) and examined by flow cytometry. In the overlay histograms, the open histograms represent staining with isotype controls. Results are representative of two experiments.

 
gp49B1 is also expressed by CD8 and CD4 T cells after LM and P815 allogeneic tumor challenge

To determine whether gp49B1 expression is a common characteristic of all activated T cells, we infected C57BL/6 mice i.p. with LM or injected allogeneic P815 (H2d) cells and tested the CD4 and CD8 T cells in PEL 10 days after challenge for binding H1.1 mAb. As Fig. 4 shows, a high level binding of H1.1 was seen in CD4 and CD8 T cells after both methods of challenge. These cells were effector cells because they were uniformly CD62L-, CD44high and 1B11high (data not shown). The gp49 protein expressed was also confirmed to be gp49B1 using the gp49A- and gp49B1-specific Abs (data not shown). Thus, gp49B1 expression is not unique to vaccinia infection, but defines Ag-activated T cells.



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  		FIGURE 4. gp49B1 is also expressed on T cells following LM infection and allogeneic P815 tumor challenge. C57 mice were infected i.p. with LM or injected with P815 cells (P815) and their PEL obtained on day 10 postchallenge were stained with anti-CD4, anti-CD8, and gp49A/B1 mAb, H1.1. The open histograms in the overlay represent staining with isotype controls. Results are representative of two experiments.

 
gp49B1 negatively regulates IFN-{gamma} production by CD8 T cells, CD4 T cells, and NK cells

The specific expression of ITIM bearing gp49B1 in the effector phase of immune response suggested that it might function to dampen the T cell effector functions. To ascertain whether this is indeed the case, we infected gp49B1-/- mice and their gp49+/+ littermate controls backcrossed into the C57BL/6 background for six generations, with vaccinia virus i.p. and examined their T cells accumulating in PEL 7 days later for their phenotype and function. There were no significant differences between gp49B1+/+ and gp49B1-/- mice in the expression of CD62L, CD25, CD69, CD44, or the effector isoform of CD43, suggesting that gp49B1 does not affect priming and activation of T cells (data not shown). To test functionality, we measured viral-specific IFN-{gamma} production and viral-specific cytotoxicity 7 days after infection. To be able to measure IFN-{gamma} production by both CD8 and CD4 T cells, we used syngeneic macrophages derived from uninfected wild-type C57 mice as targets (since they express both class I and class II molecules). Viral-specific cytotoxicity was measured using EL-4 cell targets. Because gp49B1 is also expressed by NK cells after virus infection, we also measured Ag-independent IFN-{gamma} producing and cytotoxic functions of NK cells accumulating in PEL 3 days after vaccinia infection using the NK cell sensitive target, Yac-1 cells. As shown in Fig. 5, IFN-{gamma} responses of all subsets of cells were enhanced in gp49B1-deficient mice compared with gp49+/+ mice. Although a small increase in cytotoxicity was detectable, they were not statistically significant. Collectively, these results suggest that gp49B1 selectively inhibits IFN-{gamma} response of Ag-specific CD8 T cells, CD4 T cells, and NK cells.



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  		FIGURE 5. Effector functions of CD8, CD4 T cells, and NK cells are enhanced in gp49B1-deficient mice. gp49+/+ (wild type (WT)) and gp49B1 (knockout (KO)) mice were infected with vaccinia virus and the peritoneal exudate cells harvested on day 3 (for NK cells) or day 7 (for CD8 and CD4 T cells) postinfection were tested for IFN-{gamma} production and cytotoxicity. To measure IFN-{gamma} production, the cells were stimulated for 6 h with vaccinia virus-infected adherent macrophages from wild-type mice (for CD4 and CD8 T cells) or Yac-1 cells (for NK cells), stained externally with anti-CD8 and anti-CD4 or NK1.1 mAb and intracellularly with anti-IFN-{gamma} Ab. Representative dot plot analyses are shown in the top panel. Bar graphs in the middle panel show data from six mice (from two experiments) in each category as mean values ± SD. In each bar graph except the one that shows IFN-{gamma} MFI, the difference is statistically significant (two independent experiments with three mice of each genotype per experiment; p < 0.05, paired two-tailed Student’s t test). To measure cytotoxic function, (lower panel), the peritoneal exudates cells were tested for specific lysis of vaccinia-infected EL-4 targets (anti-viral cytotoxicity) or Yac-1 targets (NK cytotoxicity) in a 4-h chromium release assay.

 
gp49B1 increases effector cell activation threshold

It has been suggested that NK-IRs regulate T cell responses by increasing their threshold for stimulation. If this is true for gp49B1, the stimulation threshold should be less for effector T cells from gp49B1-deficient mice. Indeed the threshold for IgE + Ag-induced activation of mast cells in vivo is ~10-fold lower in gp49B1-deficient mice (23). Therefore, we stimulated PELs from vaccinia-infected wild-type and gp49B1-deficient mice with graded doses of soluble anti-CD3 Ab (to allow presentation by macrophage FcR) and measured their IFN-{gamma} production. While no differences were seen with anti-CD3 >10 ng/ml, at concentrations of 1 and 0.1 ng/ml, few wild-type T cells responded, whereas a fraction (5–10%) of gp49B1-deficient T cells produced IFN-{gamma} (Fig. 6). Collectively our results suggest that gp49B1 serves to negatively regulate IFN-{gamma} production by effector cells by increasing their activation threshold.



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  		FIGURE 6. Stimulation threshold for IFN-{gamma} production decreases in the absence of gp49B1. PEL from day 7 vaccinia-infected gp49+/+ (wild type (WT)) and gp49-/- (knockout (KO)) mice were stimulated with indicated concentrations of soluble anti-CD3 Ab for 6 h and intracellular IFN-{gamma} production was measured as described in Fig. 1. Data are shown as the mean of three animals in each group ± SD. The differences seen at anti-CD3 concentrations of 1 and 0.1 ng/ml are statistically significant (p < 0.05, paired two-tailed Student’s t test). No differences were seen at anti-CD3 doses >10 ng/ml (not shown).

 

   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Although members of the lectin family of NK-IRs, such as CD94/NKG2A heterodimer and killer cell lectin-like receptor G1 (KLRG1), are expressed by murine Ag-specifc CD8 T cells during an acute viral infection (16, 17), the Ig superfamily members are not known to be expressed on T cells. We demonstrate in this work that the Ig superfamily member, gp49B1 is expressed by nearly all Ag-activated CD8 as well as CD4 T cells responding to a viral or bacterial Ag. We also show that gp49B1 inhibits IFN-{gamma} production by CD4 T cells, CD8 T cells, and NK cells following acute infection without affecting the cytotoxic function.

Our results using a number of different models of antigenic stimulation indicate that gp49B1 expression is a common feature of activated Ag-specific T cells. However, Wang et al. (20) failed to detect gp49A/B1 expression on T cells after infection with murine CMV. Probably because the focus of their study was on NK cells, they only examined splenocytes 3 days after infection, at which time, the spleen is unlikely to harbor a sufficient number of Ag-specific T cells (30). Moreover, our kinetics data also suggest that maximal expression of gp49B1 requires 4–5 days of stimulation. Thus, it is unlikely that gp49B1 is not expressed by CMV-specific T cells.

It is remarkable that gp49B1 with inhibitory potential, but not the closely related gp49A, lacking the cytoplasmic ITIM is expressed in T cells, perhaps reflecting a strong need for such regulation in T cells. However, both receptors are expressed in mast cells (19). The fact that gp49B1 is constitutively expressed in mast cells, but has to be induced in T cells by activation suggest differential transcription factor usage in these cell types. Based on coordinate expression of gp49A and gp49B1 on mast cells and their chromosomal localization to within 4.5 kb of each other, it has been postulated that these two molecules may be coordinately regulated in mast cells (19). Our results suggest that this is not the case in T cells and that they are differentially regulated at a transcriptional level.

The kinetics of gp49B1 expression in activated T cells as well as the fact that gp49B1 expression decreased in memory cells suggest that gp49B1 serves to restrain T cells when they have maximal functional capacity during an acute viral infection. In contrast, the Ig family KIRs have been generally thought to be expressed as a result of chronic, rather than acute stimulation since they are expressed in tumors and HIV infection but not after superantigen stimulation or acute infections (6, 12, 17, 31). These differences indicate that NK-IRs may not be redundant, but may control T cell functions at different time points during an immune response.

The lectin-like Ly49 family of receptors in mice behave biologically like the Ig family of KIRs in humans (reviewed in Refs.1 and2). Both groups encode numerous NK cell receptors specific for different classical MHC class I molecules, and are expressed by a fraction of CD8 T cells in a variegated, overlapping fashion, so that individual cells typically express a distinct subset of receptors. Although KIR and Ly49+ CD8 T cells specific for tumor or viral Ags can be isolated, the majority of CTLs specific for a given Ag do not express these receptors, nor are these receptors induced after acute viral infection in humans or in mice (32, 33). In contrast, the lectin-like receptor, CD94-NKG2, recognizes the nonclassical MHC molecule, HLA E (in humans) or Qa1 (in mice) complexed with peptides derived from MHC molecules and is induced in the vast majority of Ag-specific CD8 T cells during acute viral infections (13, 16, 17). Similarly, the lectin family of NK receptors with unknown ligands like NK1.1 and KLRG1 are also expressed in a majority of Ag-specific CD8 T cells after viral infection in mice (15, 16). Our results show that gp49B1, although it belongs to the Ig family, behaves like the lectin receptors CD94-NKG2A and KLRG1, because it is induced on the vast majority of CD8 T cells after antigenic stimulation. Thus, the structural classification into lectin and Ig family may not be indicative of biologic role and underscores a need for function/biology-based classification.

Inhibition of cytokine release by gp49B1 when cross engaged with stimulatory receptors has been demonstrated in NK cells in vitro (20). Our results with T cells are in accordance with these studies and further suggests that the cytokine production, but not the cytotoxic functions are affected by gp49B1. Similar dichotomy in regulating cytotoxic and cytokine production functions has been reported in NK cells for the stimulatory receptors, KIR2DL4 and 2B4 (34). When stimulated with a mAb for KIR2DL4, resting NK cells readily secreted IFN-{gamma}, but were unable to lyse target cells and in contrast, 2B4 mAb stimulated cytotoxicity but not IFN-{gamma} production. Moreover, inhibition of multiple steps in MAPK signaling abrogated cytotoxicity in the human NK cell line, YT, whereas IFN-{gamma} production could only be inhibited using specific inhibitors of p38, suggesting that different signaling pathways may be involved in cytotoxicity and cytokine release (35). Unlike other NK-IRs, which recognize MHC molecules, gp49B1 has been reported to bind the integrin {alpha}V{beta}3 (36). Although it is not known whether this is the sole or the principal ligand for gp49B1 on T cells, one possible explanation for the dichotomy we observed is that we used the ligand-expressing macrophages to present Ags or CD3 Ab for the IFN-{gamma} assays and the ligand-negative EL-4 cells for the cytotoxicity assays. However, this seems unlikely because we were unable to detect significant differences in cytotoxicity even using the {alpha}V{beta}3 expressing syngeneic lung fibroblasts as targets (data not shown). Thus, it is possible that gp49B1-generated signals could particularly affect the pathways involved in IFN-{gamma} production.

What might be the benefit of gp49B1-mediated inhibition of T and NK cell cytokine secretion during an acute infection? Several reasons have been proposed for the existence of inhibitory receptors. One view is that inhibitory receptor expression represents a mechanism to avoid over-stimulation that would otherwise lead to tissue damage, exhaustion, or activation-induced cell death (AICD) (12, 37). Forced expression of the inhibitory receptor Ly49A in transgenic mice resulted in increased LCMV titers (37). However, we did not observe significant differences in viral titers or obvious signs of tissue destruction in gp49B1-/- mice during acute vaccinia infection (data not shown). It may be that this could be more important in protracted infections. Another possibility is that gp49B1 may selectively impair the activation and expansion of T cells with low affinity TCR, thereby playing a role in determining the immunodominance of the response. Such a role for an inhibitory receptor has been shown in LY49 transgenic mice, where CTLs specific for a subdominant LCMV epitope were inhibited more strongly than those specific for dominant epitopes (37). Studies are underway to determine whether gp49B1 is involved in shaping immunodominance of the T cell response.

Based on the finding of KIR+ CTL clones specific for self Ags from melanoma patients as well as from healthy individuals, it has been proposed that inhibitory receptors may prevent auto aggression by CTLs specific for self Ag (4, 6, 38). Moreover, when the Ly49A transgene was expressed on T cells and thymocytes, the mice developed a fatal inflammatory disease suggestive of autoimmunity, possibly due to a failure to delete autoreactive T cells (39, 40). gp49B1, by raising the activation threshold of effector cells, might inhibit responses to cells that present low affinity, cross-reactive self peptides. In this context, it is noteworthy that cross-reactive CTL have been demonstrated following a number of viral infections (41, 42). Although gp49B-/- mice do not develop spontaneous autoimmunity, it will be interesting to test their proclivity to autoimmunity in experimental models.

It has also been proposed that NK-IRs may facilitate memory cell generation by inhibiting AICD of effector cells. Large numbers of memory phenotype CD8 T cells accumulate in transgenic mice expressing human KIR2DL3 and its ligand, HLA-Cw3 (43). Moreover, in vitro recognition of HLA-Cw3 down-regulates AICD of KIR2DL3-expressing CD8 T cells. Similarly, KIR+ rather than KIR- CD8 T cells in humans were capable of surviving in vitro cloning and were resistant to AICD (44). However, we did not observe overt differences between wild-type and gp49B1-deficient mice in the total number of memory phenotype (CD44high) T cells 2 mo after vaccinia infection.

In summary, our results provide evidence that gp49B1 is a unique NK-IR that can regulate the cytokine secretion functions of multiple lineages of effector cells in vivo. Further studies in gp49B1-/- mice should lead to additional insights into the regulatory functions of NK-IRs.


   Acknowledgments
 
We thank Nedim Ince and Premlata Shankar for helpful discussions, Rafi Ahmed and Susan Kaech for help in gene chip analysis, and Lin Li for technical assistance.


   Footnotes
 
1 Address correspondence and reprint requests to Dr. Manjunath N, Center for Blood Research, Harvard Medical School, 800 Huntington Avenue, Boston, MA 02115. E-mail address: Swamy{at}cbr.med.harvard.edu Back

2 Abbreviations used in this paper: NK-IR, NK cell-associated inhibitory receptor; MFI, mean fluorescent intensity; PEL, peritoneal exudate lymphocyte; LM, Listeria monocytogenes; ITIM, immunoreceptor tyrosine-based inhibitory motif; KIR, killer cell Ig-like receptor; LCMV, lymphocytic choriomeningitis virus; AICD, activation-induced cell death; KLRG1, killer cell lectin-like receptor G1. Back

Received for publication December 17, 2002. Accepted for publication February 6, 2003.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. McMahon, C. W., D. H. Raulet. 2001. Expression and function of NK cell receptors in CD8+ T cells. Curr. Opin. Immunol. 13:465.[Medline]
  2. Raulet, D. H., R. E. Vance, C. W. McMahon. 2001. Regulation of the natural killer cell receptor repertoire. Annu. Rev. Immunol. 19:291.[Medline]
  3. Mingari, M. C., C. Vitale, A. Cambiaggi, F. Schiavetti, G. Melioli, S. Ferrini, A. Poggi. 1995. Cytolytic T lymphocytes displaying natural killer (NK)-like activity: expression of NK-related functional receptors for HLA class I molecules (p58 and CD94) and inhibitory effect on the TCR-mediated target cell lysis or lymphokine production. Int. Immunol. 7:697.[Abstract/Free Full Text]
  4. Noppen, C., C. Schaefer, P. Zajac, A. Schutz, T. Kocher, J. Kloth, M. Heberer, M. Colonna, G. De Libero, G. C. Spagnoli. 1998. C-type lectin-like receptors in peptide-specific HLA class I-restricted cytotoxic T lymphocytes: differential expression and modulation of effector functions in clones sharing identical TCR structure and epitope specificity. Eur. J. Immunol. 28:1134.[Medline]
  5. Le Drean, E., F. Vely, L. Olcese, A. Cambiaggi, S. Guia, G. Krystal, N. Gervois, A. Moretta, F. Jotereau, E. Vivier. 1998. Inhibition of antigen-induced T cell response and antibody-induced NK cell cytotoxicity by NKG2A: association of NKG2A with SHP-1 and SHP-2 protein-tyrosine phosphatases. Eur. J. Immunol. 28:264.[Medline]
  6. Speiser, D. E., M. J. Pittet, D. Valmori, R. Dunbar, D. Rimoldi, D. Lienard, H. R. MacDonald, J. C. Cerottini, V. Cerundolo, P. Romero. 1999. In vivo expression of natural killer cell inhibitory receptors by human melanoma-specific cytolytic T lymphocytes. J. Exp. Med. 190:775.[Abstract/Free Full Text]
  7. De Maria, A., A. Ferraris, M. Guastella, S. Pilia, C. Cantoni, L. Polero, M. C. Mingari, D. Bassetti, A. S. Fauci, L. Moretta. 1997. Expression of HLA class I-specific inhibitory natural killer cell receptors in HIV-specific cytolytic T lymphocytes: impairment of specific cytolytic functions. Proc. Natl. Acad. Sci. USA 94:10285.[Abstract/Free Full Text]
  8. Sirianni, M. C., F. Ensoli, C. Alario, V. Fiorelli, G. Sacco, S. Topino, F. Iebba, I. Mezzaroma, F. Aiuti. 2001. Distribution of the natural killer-related receptor for HLA-C during highly active antiretroviral therapy for human immunodeficiency virus infection. Hum. Immunol. 62:1328.[Medline]
  9. Galiani, M. D., E. Aguado, R. Tarazona, P. Romero, I. Molina, M. Santamaria, R. Solana, J. Pena. 1999. Expression of killer inhibitory receptors on cytotoxic cells from HIV-1-infected individuals. Clin. Exp. Immunol. 115:472.[Medline]
  10. Costa, P., S. Rusconi, D. Mavilio, M. Fogli, G. Murdaca, D. Pende, M. C. Mingari, M. Galli, L. Moretta, A. De Maria. 2001. Differential disappearance of inhibitory natural killer cell receptors during HAART and possible impairment of HIV-1-specific CD8 cytotoxic T lymphocytes. AIDS 15:965.[Medline]
  11. De Maria, A., L. Moretta. 2000. HLA-class I-specific inhibitory receptors in HIV-1 infection. Hum. Immunol. 61:74.[Medline]
  12. De Maria, A., D. Mavilio, P. Costa, P. Dignetti, M. Fogli, M. C. Mingari. 2000. Multiple HLA-class I-specific inhibitory NK receptor expression and IL- 4/IL-5 production by CD8+ T-cell clones in HIV-1 infection. Immunol Lett 72:179.[Medline]
  13. Moser, J. M., J. Gibbs, P. E. Jensen, A. E. Lukacher. 2002. CD94-NKG2A receptors regulate antiviral CD8+ T cell responses. Nat Immunol 3:189.[Medline]
  14. Kambayashi, T., E. Assarsson, J. Michaelsson, P. Berglund, A. D. Diehl, B. J. Chambers, H. G. Ljunggren. 2000. Emergence of CD8+ T cells expressing NK cell receptors in influenza A virus-infected mice. J. Immunol. 165:4964.[Abstract/Free Full Text]
  15. Slifka, M. K., R. R. Pagarigan, J. L. Whitton. 2000. NK markers are expressed on a high percentage of virus-specific CD8+ and CD4+ T cells. J. Immunol. 164:2009.[Abstract/Free Full Text]
  16. Miller, J. D., M. Peters, A. E. Oran, G. W. Beresford, L. Harrington, J. M. Boss, J. D. Altman. 2002. CD94/NKG2 Expression does not inhibit cytotoxic function of lymphocytic choriomeningitis virus-specific CD8+ T cells. J. Immunol. 169:693.[Abstract/Free Full Text]
  17. McMahon, C. W., A. J. Zajac, A. M. Jamieson, L. Corral, G. E. Hammer, R. Ahmed, D. H. Raulet. 2002. Viral and bacterial infections induce expression of multiple NK cell receptors in responding CD8+ T cells. J. Immunol. 169:1444.[Abstract/Free Full Text]
  18. Castells, M. C., X. Wu, J. P. Arm, K. F. Austen, H. R. Katz. 1994. Cloning of the gp49B gene of the immunoglobulin superfamily and demonstration that one of its two products is an early-expressed mast cell surface protein originally described as gp49. J. Biol. Chem. 269:8393.[Abstract/Free Full Text]
  19. McCormick, M. J., M. C. Castells, K. F. Austen, H. R. Katz. 1999. The gp49A gene has extensive sequence conservation with the gp49B gene and provides gp49A protein, a unique member of a large family of activating and inhibitory receptors of the immunoglobulin superfamily. Immunogenetics 50:286.[Medline]
  20. Wang, L. L., D. T. Chu, A. O. Dokun, W. M. Yokoyama. 2000. Inducible expression of the gp49B inhibitory receptor on NK cells. J. Immunol. 164:5215.[Abstract/Free Full Text]
  21. Lee, K. H., M. Ono, M. Inui, T. Yuasa, T. Takai. 2000. Stimulatory function of gp49A, a murine Ig-like receptor, in rat basophilic leukemia cells. J. Immunol. 165:4970.[Abstract/Free Full Text]
  22. Lu-Kuo, J. M., D. M. Joyal, K. F. Austen, H. R. Katz. 1999. gp49B1 inhibits IgE-initiated mast cell activation through both immunoreceptor tyrosine-based inhibitory motifs, recruitment of src homology 2 domain-containing phosphatase-1, and suppression of early and late calcium mobilization. J. Biol. Chem. 274:5791.[Abstract/Free Full Text]
  23. Daheshia, M., D. S. Friend, M. J. Grusby, K. F. Austen, H. R. Katz. 2001. Increased severity of local and systemic anaphylactic reactions in gp49B1-deficient mice. J. Exp. Med. 194:227.[Abstract/Free Full Text]
  24. Manjunath, N., P. Shankar, J. Wan, W. Weninger, M. A. Crowley, K. Hieshima, T. A. Springer, X. Fan, H. Shen, J. Lieberman, U. H. von Andrian. 2001. Effector differentiation is not prerequisite for generation of memory cytotoxic T lymphocytes. J. Clin. Invest. 108:871.[Medline]
  25. Pircher, H., K. Burki, R. Lang, H. Hengartner, R. M. Zinkernagel. 1989. Tolerance induction in double specific T-cell receptor transgenic mice varies with antigen. Nature 342:559.[Medline]
  26. Katz, H. R., E. Vivier, M. C. Castells, M. J. McCormick, J. M. Chambers, K. F. Austen. 1996. Mouse mast cell gp49B1 contains two immunoreceptor tyrosine-based inhibition motifs and suppresses mast cell activation when coligated with the high-affinity Fc receptor for IgE. Proc. Natl. Acad. Sci. USA 93:10809.[Abstract/Free Full Text]
  27. Manjunath, N., M. Correa, M. Ardman, B. Ardman. 1995. Negative regulation of T-cell adhesion and activation by CD43. Nature 377:535.[Medline]
  28. Manjunath, N., P. Shankar, B. Stockton, P. D. Dubey, J. Lieberman, U. H. von Andrian. 1999. A transgenic mouse model to analyze CD8+ effector T cell differentiation in vivo. Proc. Natl. Acad. Sci. USA 96:13932.[Abstract/Free Full Text]
  29. Harrington, L. E., M. Galvan, L. G. Baum, J. D. Altman, R. Ahmed. 2000. Differentiating between memory and effector CD8 T cells by altered expression of cell surface O-glycans. J. Exp. Med. 191:1241.[Abstract/Free Full Text]
  30. Kedl, R. M., M. F. Mescher. 1997. Migration and activation of antigen-specific CD8+ T cells upon in vivo stimulation with allogeneic tumor. J. Immunol. 159:650.[Abstract]
  31. Bertone, S., F. Schiavetti, R. Bellomo, C. Vitale, M. Ponte, L. Moretta, M. C. Mingari. 1999. Transforming growth factor-{beta}-induced expression of CD94/NKG2A inhibitory receptors in human T lymphocytes. Eur. J. Immunol. 29:23.[Medline]
  32. Mingari, M. C., F. Schiavetti, M. Ponte, C. Vitale, E. Maggi, S. Romagnani, J. Demarest, G. Pantaleo, A. S. Fauci, L. Moretta. 1996. Human CD8+ T lymphocyte subsets that express HLA class I-specific inhibitory receptors represent oligoclonally or monoclonally expanded cell populations. Proc. Natl. Acad. Sci. USA 93:12433.[Abstract/Free Full Text]
  33. Peacock, C. D., M. Y. Lin, J. R. Ortaldo, R. M. Welsh. 2000. The virus-specific and allospecific cytotoxic T-lymphocyte response to lymphocytic choriomeningitis virus is modified in a subpopulation of CD8+ T cells coexpressing the inhibitory major histocompatibility complex class I receptor Ly49G2. J. Virol. 74:7032.[Abstract/Free Full Text]
  34. Rajagopalan, S., J. Fu, E. O. Long. 2001. Cutting edge: induction of IFN-{gamma} production but not cytotoxicity by the killer cell Ig-like receptor KIR2DL4 (CD158d) in resting NK cells. J. Immunol. 167:1877.[Abstract/Free Full Text]
  35. Chuang, S. S., P. R. Kumaresan, P. A. Mathew. 2001. 2B4 (CD244)-mediated activation of cytotoxicity and IFN-{gamma} release in human NK cells involves distinct pathways. J. Immunol. 167:6210.[Abstract/Free Full Text]
  36. Castells, M. C., L. B. Klickstein, K. Hassani, J. A. Cumplido, M. E. Lacouture, K. F. Austen, H. R. Katz. 2001. gp49B1-{alpha}v{beta}3 interaction inhibits antigen-induced mast cell activation. Nat. Immunol. 2:436.[Medline]
  37. Zajac, A. J., R. E. Vance, W. Held, D. J. Sourdive, J. D. Altman, D. H. Raulet, R. Ahmed. 1999. Impaired anti-viral T cell responses due to expression of the Ly49A inhibitory receptor. J. Immunol. 163:5526.[Abstract/Free Full Text]
  38. Huard, B., L. Karlsson. 2000. A subpopulation of CD8+ T cells specific for melanocyte differentiation antigens expresses killer inhibitory receptors (KIR) in healthy donors: evidence for a role of KIR in the control of peripheral tolerance. Eur. J. Immunol. 30:1665.[Medline]
  39. Fahlen, L., L. Oberg, T. Brannstrom, N. K. Khoo, U. Lendahl, C. L. Sentman. 2000. Ly49A expression on T cells alters T cell selection. Int. Immunol. 12:215.[Abstract/Free Full Text]
  40. Pauza, M., K. M. Smith, H. Neal, C. Reilly, L. L. Lanier, D. Lo. 2000. Transgenic expression of Ly-49A in thymocytes alters repertoire selection. J. Immunol. 164:884.[Abstract/Free Full Text]
  41. Kim, S. K., M. A. Brehm, R. M. Welsh, L. K. Selin. 2002. Dynamics of memory T cell proliferation under conditions of heterologous immunity and bystander stimulation. J. Immunol. 169:90.[Abstract/Free Full Text]
  42. Brehm, M. A., A. K. Pinto, K. A. Daniels, J. P. Schneck, R. M. Welsh, L. K. Selin. 2002. T cell immunodominance and maintenance of memory regulated by unexpectedly cross-reactive pathogens. Nat Immunol 3:627.[Medline]
  43. Ugolini, S., C. Arpin, N. Anfossi, T. Walzer, A. Cambiaggi, R. Forster, M. Lipp, R. E. Toes, C. J. Melief, J. Marvel, E. Vivier. 2001. Involvement of inhibitory NKRs in the survival of a subset of memory- phenotype CD8+ T cells. Nat Immunol 2:430.[Medline]
  44. Young, N. T., M. Uhrberg, J. H. Phillips, L. L. Lanier, P. Parham. 2001. Differential expression of leukocyte receptor complex-encoded Ig-like receptors correlates with the transition from effector to memory CTL. J. Immunol. 166:3933.[Abstract/Free Full Text]



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