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Department of Microbiology, University of Tennessee, Knoxville, TN 37996
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionDisclosuresReferences |
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in the latent TG. In this report we demonstrated that activated virus-specific memory CD8+ T cells, although potentially cytolytic, also expressed the CD94-NK cell receptor subfamily G2a inhibitory molecule and were unable to exert cytotoxicity when engaged by Qa-1b expressing targets. Interestingly, many neurons in the latent TG expressed Qa-1b, and blocking of Qa-1b/CD94-NKG2a interaction in an ex vivo TG culture resulted in neuronal cell lysis. The expression of the inhibitory CD94-NKG2a molecule could be induced by TGF-
1, which was shown to present as a bioactive molecule in the latent TG. Additionally, CD4+ forkhead/winged helix transcription factor 3+ T cells were also determined in the latent TG. Our results demonstrate the operation of a regulatory system in vivo that serves to protect irreplaceable neurons from destruction by the immune system. |
Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionDisclosuresReferences |
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produced by the CD8+ T cells (7). However, because IFN- production requires more Ag to be recognized than does the release of lytic granules (8), it is perhaps surprising that the neurons are not killed by the cytolytic action of the CD8+ T cells.
A number of explanations are possible. These include inhibitory effects on the cytotoxicity process either as a consequence of engagement of inhibitory receptors on the CD8+ T cells or because of the inhibitory effects mediated by other cell types that compose the inflammatory response. This report provides evidence for the former mechanism. We demonstrate that although most of the virus-specific CD8+ T cells in the latent TG possess lytic granules, they also express NK inhibitory receptors, such as CD94/NK cell receptor subfamily G2a (NKG2a) and killer cell lectin-like receptor subfamily G1 (KLRG1). Furthermore, the expression of CD94/NKG2a is regulated by the presence of TGF-1 in the latent TG. Additionally, a significant number of CD4+ forkhead/winged helix transcription factor (Foxp3)+ regulatory T (Treg) cells are observed in the latent TG. Interestingly, 
35% of neurons in the latent TG express Qa-1b, the major ligand for the CD94-NKG2a receptor (9), and in vitro blocking of the Qa-1b/CD94-NKG2a interaction resulted in enhanced cytolytic activity of ganglionic CD8+ T cells. Our results demonstrate the operation of a regulatory system in vivo that serves to protect irreplaceable neurons from destruction by the immune system.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionDisclosuresReferences |
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Female 6- to 8-wk-old C57BL/6 (B6) mice were purchased from Harlan Sprague Dawley. All investigations followed the guidelines of the committee on the care of laboratory animal resources, Commission on Life Science, National Research Council. A dose of 2 x 105 PFU of HSV-1 RE/eye was used to infect B6 mice. Biotinylated anti-Qa-1b, KLRG1, CD94, PerCP-anti-CD8
, anti-CD4, FITC-labeled anti-CD25, PE anti-IL-7r, and purified anti-Qa-1b (NA/LE) Abs and streptavidin-PE were obtained from BD Biosciences. FITC-labeled perforin, anti-NKG2a and PE-labeled anti-NKG2a, anti-Ly49 C/I, and anti-mouse Foxp3 mAb were obtained from eBiosciences. Biotin-labeled anti-human granzyme B Ab, biotinylated mouse IgG1 isotype, purified rat IgG2a, mouse IgG1, and goat anti-mouse IgG1 isotype was obtained from Caltag Laboratories. AlexaFluor 488-conjugated and biotinylated mouse anti-NeuN mAb was procured from Chemicon International. Recombinant TGF-1; purified anti-TGF-1, -2, and -3; and anti-TGF-1 biotin-labeled Abs were obtained from R&D Systems.
Isolation and flow cytometric analysis of TG
TG excised 28 days after ocular infection were considered latent TG and were digested with liberase (Roche) at 37°C for 1 h in complete RPMI 1640 medium (Sigma-Aldrich). A single-cell suspension of TG was made with a 3-ml syringe plunger, and total cell count was determined in trypan blue. For flow cytometry, 8 x 105 cells/well were used for cell surface and intracellular staining of the neuron nucleus, and a total of 500,000 events were collected. For intracellular staining, surface-labeled cells were permeabilized with permeabilization buffer (BD Biosciences). Data were analyzed using CellQuest Pro software (BD Biosciences).
CD8+ T cell purification from TG and ex vivo CTL assay
A total of 22 TG from HSV-infected B6 mice (28 days after infection) were pooled, and a single-cell suspension was obtained using Liberase CI (Roche) at 37°C for 1 h. CD8+ T cells were enriched from latent TG using a MACS anti-CD8 microbead system (Miltenyi Biotec). CD8+ T cells from enriched samples were sorted using the FACSVantage SE system (BD Biosciences). The purity of CD8+ T cells from enriched samples was >90%. Ex vivo CTL activity was assessed by a 4-h 51Cr release assay against labeled MC-38 target cells. In certain experiments, Qa-1b+ MC-38 cells were sorted and used as targets. Targets were pulsed with two different concentrations of SSIEFARL peptide (2 or 0.2 µM) and labeled with 100 µCi of 51Cr for 1 h and 30 min before coculture with purified CD8+ T cells. Qa-1b-blocking experiments were performed as reported by Moser et al. (10). Briefly, 51Cr-labeled MC-38 cells were pulsed with peptides in the presence of brefeldin A (10 µg/ml) for 1 h and 30 min at 37°C. This was followed by incubating the targets with anti-mouse Qa-1b or control Ab (mouse IgG1, 20 µg/ml) at 22°C for 20 min in 1% FBS and DMEM. Lastly, targets were incubated with goat anti-mouse IgG1 Ab (20 µg/ml) in DMEM before coculture with CD8+ T cells. The percent specific lysis was calculated as described previously (11)
Calcein release assay
Neuronal cell lysis was quantified by the calcein release assay as described previously (12, 13). Briefly, a single-cell suspension of the latent TG samples was incubated at 37°C in a water bath for 30 min with 2 µg/ml calcein-AM (Molecular Probes) in 200 µl of PBS. This led to the uptake of nonfluorescent calcein by neurons and the other cells in the total TG cell culture. Inside the cell, calcein-AM was de-esterified to a polar fluorescent product (emission, 517 nm; FL1), which was retained in intact cells and released only after membrane damage. Calcein-loaded cells were washed twice in HBSS to remove the free residual dye. The final TG cell concentration was adjusted to 1.0 x 107/ml and pulsed with SSIEFARL peptide (0.2 µm) for 4 h at 37°C in complete RPMI 1640 medium. In certain wells, calcein-labeled latent TG cell culture was not pulsed with SSIEFARL peptide and was incubated at 37°C for 4 h. Qa-1b-blocking studies were conducted as described above. TG cell culture from uninfected mice was used as the negative control. All assays were seeded in triplicate in 48-well plates. After incubating the plates for 4 h, the cells were pelleted, and 200 µl of supernatant was transferred into a 96-well plate and measured for the fluorescence using an automated fluorescence reader (Victor; EG/G Wallac). The percentage of total cell lysis in TG culture was calculated as follows: 100 x ((test fluorescence – spontaneous fluorescence)/(maximum fluorescence – spontaneous fluorescence)). To specifically address the neuronal cell lysis, calcein-labeled cells from the 48-well plate were intracellularly stained with biotinylated anti-mouse neu-N mAb, followed by streptavidin-PE. Biotinylated mouse IgG1 was used as an isotype-matched control. The FACS plot was gated on Neu-N+ cells, and the percent lysis of Neu-N+ cells was calculated as follows: 100 x (% of neu-N+ cells in control Ab treated well – % of neu-N+ cells in anti-Qa-1b Ab treated well)/% of neu-N+ cells in control Ab-treated wells.
RT-PCR for TGF-1 and IL-10
Total cellular RNA was isolated from TG using an RNeasy Protect Mini Kit (Qiagen) according to the manufacturer’s instructions. All samples were treated with RNase-free DNase (Qiagen). The extracted RNA was reverse transcribed using oligo(dT) primers and reverse transcriptase enzyme (Promega) according to standard protocol. The cDNA obtained was used as a template for semiquantitative RT-PCR assay. The PCR primer pairs used were: GAPDH, 5'-GCC TGC TTC ACC ACC TTC TTG ATG-3' and 5'-CAT CCT GCA CCA CCA ACT GCT TAG-3'; IL-10, 5'-GGT TGC CAA GCC TTA TCG GA-3' and 5'-ACC TGC TCC ACT GCC TTG CT-3'; and TGF-1, 5'-TGA CGT CAC TGG AGT TGT ACG G-3' and 5'-GGT TCA TGT CAT GGA TGG TGC-3'.
PC61 treatment
PC61 (anti-CD25) hybridoma was purchased from American Type Culture Collection, and Ab was grown as ascites fluid in the nude mice. A dose of 500 µg/mouse was used in the latently infected B6 animals (day 28 postinfection (p.i.)), and mice were killed on day 4 p.i. The control group of animals received rat Ig isotype, and TG isolated from test or control groups were either liberase digested for flow cytometry or sonicated to ascertain the level of TGF-1 protein by ELISA.
Latent TG sonication and cytokine ELISA
Latent TG was excised 28 days p.i. from ocularly infected B6 mice, and a single TG obtained from each mouse was sonicated in 250 µl of lysis buffer using an ultrasonicator. The lysate was examined for the presence of IL-10 and TGF-1 protein as described previously (14). Briefly, plates were coated with anti-IL-10 or TGF-1 mAb in 0.1 M Na2HPO4 buffer at 4°C overnight; the next day, plates were blocked with PBS-3% BSA before the addition of TG lysate. Anti-IL-10 and TGF-1 biotin-labeled mAb in PBS-1% BSA were added for 1 h at 37°C, followed by the addition of streptavidin-HRP (Jackson ImmunoResearch Laboratories) for 30 min. The color was developed by adding the substrate (ABTS) solution (Sigma-Aldrich), and the concentration was calculated with an automated ELISA reader (SpectraMAX 340; Molecular Devices).
Immunofluorescence staining of Foxp3 in TG
For immunofluorescence, sections were air-dried and fixed in methanol/acetone (1/1) at –20°C for 10 min. This was followed by blocking with PBS-3% BSA containing a 1/200 dilution of Fc block (clone 2.4G2; BD Pharmingen) for 2 h. Sections were incubated with anti-Foxp3 FITC-labeled mAb (eBiosciences) overnight at 4°C in PBS-1% BSA. Rat IgG-FITC was used as an isotype-matched control. Finally, propidium iodide was used to counterstain the slides (Vectashield with propidium iodide; Vector Laboratories). Images were captured with a Leica SP2 laser scanning confocal microscopy (Leica).
Statistical analysis
All analyses for statistically significant differences were performed with Student’s paired t test. A value of p 
0.01 was considered significant. Results are expressed as the mean ± SD.
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Results |
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Four weeks after ocular HSV infection, a time when replicating virus is no longer evident (15), we confirmed a previous report (4) that >90% of CD8+ T cells recovered from the TG expressed the CD69 activation marker (data not shown). Moreover, most of them also expressed IL-7r (Fig. 1a), a phenotype characteristic of memory CD8+ T cells (16). To determine whether CD8+ T cells were potentially cytotoxic, the intracellular expression of granzyme B and perforin was measured in both total (data not shown) and SSIEFARL-specific CD8+ T cells isolated from the TG by tetramer staining. As shown in Fig. 1b, the majority of Ag-specific cells expressed granzyme B and perforin consistent with their ability to be cytolytic. However, although highly activated and cytolytically competent, control of infection in affected neurons appeared to proceed without neuronal destruction (7). We hypothesized that the reason cytotoxic CD8+ T cells failed to destroy neurons was because their cytotoxicity was inhibited in some way.
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80% of double-positive cells coexpressed the CD94 molecule. Taken together, these results indicate that HSV-specific memory CD8+ T cells in the latent TG, although potentially cytolytic, nevertheless also express NK inhibitory receptors that might regulate the cytolytic potential of these cells.
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We determined that CD8+ T cells in the latent TG expressed the CD94/NKG2a receptor and hypothesized that signaling through them might contain the cytotoxicity of CD8+ T cells. The cytotoxic potential of purified CD8+ T cells obtained from multiple latent TG was determined by an ex vivo CTL assay using MC-38 (a colon carcinoma cell line) as target cells. As shown in Fig. 3a, 50% of MC-38 cells expressed the Qa-1b molecule. Target cells were pulsed with two different concentrations (2.0 and 0.2 µM) of SSIEFARL peptide and were cocultured with purified CD8+ T cells obtained from latent TG as described in Materials and Methods. In these experiments, the effect of blocking the Qa-1b-CD94-NKG2a interaction on the level of cytotoxicity was also determined. At both peptide doses, CD8+ T cells obtained from latent TG exhibited significant levels of cytotoxicity (Fig. 3b). In addition, blocking of the Qa-1b-CD94-NKG2a interaction significantly enhanced the killing of target cells (p < 0.001), but only when latter were pulsed with a lower dose of peptide. Because the target cells used were a mixture of Qa-1b+ and Qa-1b– cells, the population was sorted into Qa-1b– and Qa-1b+ MC-38 cells, and cytotoxicity was compared against both targets pulsed with the lower dose of peptide (0.2 µm). In addition, in certain wells, the Qa-1b interaction was blocked with anti-Qa-1b mAb. As shown in Fig. 3d, blocking the Qa-1b-CD94-NKG2a inhibitory receptor interaction significantly (p < 0.001) affected the lysis of Qa-1b+, but not the Qa1b– target cells (Fig. 3c). Thus, our results clearly demonstrated that interaction between Qa-1b and CD94-NKG2a suppressed the cytolytic activity of HSV-specific memory CD8+ T cells, especially when the targets expressed lower levels of peptide.
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CD8+ T cells in the latent TG predominantly expressed CD94/NKG2a and were unable to exert their cytotoxicity in the presence of the Qa-1b+ target cell line. To determine whether Qa-1b is expressed on cells in latent TG, single-cell TG suspensions were stained for the Qa-1b molecule and analyzed by flow cytometry. As shown in Fig. 4a, 27% of the total cells in the latent TG expressed Qa-1b. To determine whether neurons expressed the Qa-1b molecule, the latter cells were marked with a neuron-specific Ab (anti-neuN) that stains neuronal nuclei (18). As shown in Fig. 4b, 28, 48, and 35% of neuN+ cells coexpressed the Qa-1b molecule in naive, acute, and latent TG, respectively. Although the difference in the percentage of Qa-1b-expressing neuN+ cells was not statistically significant between naive and latent TG, the mean fluorescence intensity of Qa-1b staining was significantly higher on neuN+ cells in the latent TG, as determined by flow cytometry (Fig. 4c). In addition to neu-N+ cells, CD11b+ cells were the second major population that coexpressed Qa-1b molecule in the latent TG (Fig. 4d), and only a minor fraction of CD4+ T cells (4%) expressed Qa-1b (Fig. 4d).
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5% when the biotinylated mouse IgG1 isotype was used to stain neuN+ cells in latent TG (data not shown). Thus, our results clearly demonstrated that blocking the Qa-1b-CD94-NKG2a interaction in the TG resulted in neuronal cell lysis.
TGF-1 expression in latent TG regulates NKG2a expression on memory CD8+ T cells
Recently, it was reported that CD94-NKG2a expression could be enhanced on Ag-specific CD8+ T cells in the presence of TGF-1 (19). To determine the expression of immunosuppressive cytokines IL-10 and TGF-1 in the latent TG, either RNA was isolated from TG to perform RT-PCR (Fig. 5a), or protein expression was determined in the TG lysate by an ELISA. As shown in Fig. 5b, latent TG expressed 3-fold higher levels of TGF-1 protein compared with naive TG, but no significant IL-10 protein expression (data not shown) was evident in either naive or latent TG. Because TGF-1 can be expressed in both latent and bioactive forms (20), we measured the form of TGF-1 present in the latent TG using an assay that detects bioactive TGF-1 via its ability to inhibit IL-4-induced HT-2 cellular proliferation (21). We noted (Fig. 5c) that the latent TG lysate (obtained after sonication) significantly inhibited IL-4-induced HT-2 cell proliferation in a dose-dependent manner, with the inhibitory effect being reversed in the presence of a mixture of anti-TGF-1, -2, and -3 mAb (20 µg/ml). We also addressed whether TGF-1 expression in the latent TG could regulate CD94-NKG2a expression on memory CD8+ T cells and enhanced their cytolytic activity. As shown in Fig. 5, addition of anti-TGF- Abs to the latent TG culture not only down-regulated CD94-NKG2a expression on CD8+ T cells (Fig. 5d), but also significantly enhanced their cytolytic activity when cocultured with Qa-1b+ MC-38 target cells (Fig. 5e). Taken together, our results demonstrated that TGF-1 expression in the latent TG significantly enhanced the expression of the CD94-NKG2a molecule and thus controlled their cytotoxicity.
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TGF-1 is secreted by multiple cell types, including certain regulatory CD4+ T cell types (22). Previously, we determined that CD4+CD25+ Treg influenced the expression of corneal pathology after ocular HSV infection (23). To determine whether CD4+CD25+Foxp3+ T cells were the potential source of TGF-1 in latent TG, the presence of CD4+CD25+ or CD4+Foxp3+ Treg cells was ascertained in TG p.i. As shown in Fig. 6a, CD4+CD25+ T cells were present in the TG of HSV-infected B6 mice during acute (day 9) and latent (day 28) phases of infection. Similarly, CD4+Foxp3+ T cells were also found in TG during both the acute and latent phases (Fig. 6a). However, the percentage (9%) as well as the number (1450 ± 60) of Foxp3+CD4+ T cells were significantly higher in the latent compared with the acute TG (560 ± 48; 3%), as determined by flow cytometry and immunofluorescence (Fig. 6b). To ascertain whether CD4+CD25+ Treg were the likely source of TGF-1 expression in latent TG, B6 animals were treated (28 days p.i.) with PC61 mAb to deplete endogenous CD25+ cells. The TG, excised 4 days after depletion from control rat Ig-treated and CD25-depleted animals, were either liberase digested or sonicated to determine the extent of CD25 depletion by flow cytometry or to measure the level of TGF-1 by ELISA. PC61 mAb treatment almost completely depleted CD4+CD25+ T cells (Fig. 6c). Remarkably, 4% of CD4+Foxp3+ T cells were still evident in the latent TG of PC61-treated animals (Fig. 6c). Furthermore, as shown in Fig. 6d, CD25 depletion to some extent decreased (21%) the TGF-1 protein level in latent TG compared with isotype-treated animals. We also compared the percentage of NKG2a-expressing CD8+ T cells in the TG of depleted and nondepleted animals. No significant difference in the percentage of CD8+NKG2a+ T cells was evident between the two groups (data not shown). Taken together, our results indicate that CD4+CD25+ T cells were present in latent TG, but they did not appear to be the major source of TGF-1.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionDisclosuresReferences |
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1, which was shown to present as a bioactive molecule in the latent TG. Our results demonstrate the operation of a regulatory system in vivo that serves to protect irreplaceable neurons from destruction by the immune system. The chronic inflammatory response that occurs in the TG after infection of the face with HSV is dominated by CD8+ T cells, many of which are virus specific (4). These cells retain activation markers and are assumed to recognize HSV-infected neurons and cause them to discard viral components (24). However, if indeed infected neurons can be recognized by CD8+ T cells, it is difficult to understand why neurons will not be lysed. Our results show that the CD8+ T cells present in latent TG contain cytolytic granules such as granzyme B and perforin and, hence, have the potential to kill target cells. However, we also observed that the majority of TG CD8+ T cells expressed the NK inhibitor receptors CD94-NKG2a. Such receptors have been noted to be present on CD8+ T cells reactive with several other pathogens (25), but only in certain circumstances are these receptors functional (26). The major ligand for NKG2a inhibitory receptors is Qa-1b, a nonclassical MHC class Ib molecule that is capable of presenting endogenous as well as exogenous peptides (27). In a persistent virus-induced tumor model, the interaction between Qa-1b and CD94-NKG2a paralyzed the cytolytic activity of tumor-specific CD8+ T cells (10), but such effects were suggested not to occur with certain virus-specific CD8+ T cell responses (26). We determined that CD8+ T cells purified from latent TG were unable to exert their cytotoxicity when cocultured with peptide-pulsed Qa-1b+MC-38 target cells. However, blocking the Qa-1b interaction with CD94-NKG2a receptor resulted in target cell lysis, as determined by a chromium release assay. Moreover, it should be noted that blocking was effective only at the lower dose of peptide and, hence, significantly enhanced the killing of target cells (p < 0.001). It is possible that in the presence of a large antigenic peptide load, the higher avidity TCR-peptide MHC complex will provide a much stronger TCR stimulus, which can override the Qa-1b-CD94-NKG2a inhibitory interaction, as shown in Fig. 3b. Thus, Qa-1b-CD94-NKG2a inhibitory signaling was more effective in the presence of fewer viral Ags, a situation that presumably occurs in the latent TG (28). This could be a major regulatory pathway to inhibit the cytotoxicity of CD8+ T cells in the latent TG, where Ag doses will be low, but presumably not in the acutely inflamed TG, where replicating virus and abundant Ag are still present (28).
Qa-1b expression has been reported on a wide range of tissues, although the level of expression was always lower than that of classical class Ia molecules (29). Qa-1b was also reported to be expressed on the surface of the suppressor-inducer subset of CD4+ T cells (30). Neurons in the mouse are considered not to express classical MHC class Ia molecules under resting conditions (31), but whether the expression of nonclassical MHC class I molecules can occur is uncertain. Our results clearly demonstrated the presence of the Qa-1b molecule on TG neurons, and expression levels were significantly higher in the acute as well as the latent TG compared with naive TG neurons. IFN- was previously reported to enhance the expression of Qa-1b (32). After ocular HSV infection, IFN- is present in both acute and latent TG (7) and might contribute to regulate the expression of the Qa-1b molecule on neurons in the TG. Thus our results are consistent with the hypothesis that CTLs in latent TG may not kill Qa-1b-expressing target neuronal cells.
Additional studies with ex vivo TG cultures showed that blocking the Qa-1b-CD94-NKG2a interaction resulted in the lysis of neu-N+ cells regardless of the addition of SSIEFARL peptide to the TG culture. Although a high percentage of CD8+ T cells in latent TG are known to recognize SSIEFARL peptide (4), we were unable to evaluate whether the neuronal cell lysis observed after blocking the Qa-1b-CD94-NKG2a interaction was SSIEFARL peptide specific. Thus, levels of neuronal lysis were unaffected by the exogenous addition of SSIEFARL peptide. It is likely that SSIEFARL does not bind efficiently to the Qa-1b molecule expressed on neurons, because Qa-1b binds predominantly to a nonamer peptide (AMAPRTLLL) derived from the leader peptide sequence of the classical MHC class Ia molecule, named Qa-1 determinant modifier (Qdm) (33). However, Qa-1b can also bind to viral protein-derived peptide sequences that have homology with Qdm (34). Thus, a peptide sequence derived from one of the herpes simplex virus proteins that is homologous to Qdm might bind to Qa-1b. However, the identity of any such peptide motif is currently not known.
A final point of interest is to understand the regulatory mechanism that maintains the expression of NKG2a inhibitory receptors on the majority of CD8+ T cells present in the latent TG. Previous in vitro observations had indicated that the expression of the CD94-NKG2a molecule on Ag-specific CD8+ T cells could be enhanced by TGF-1 (19, 35). Our results show that the bioactive form of TGF-1 was present in the inflamed latent TG (day 28 p.i.) long after initial viral infection and thus controls the cytolytic activity of CD8+ T cells in latent TG by maintaining the cell surface expression of the CD94-NKG2a molecule. One potential cellular source of TGF-1 could have been CD4+CD25+ regulatory T cells (22). Such cells were demonstrated to be present in latent TG. However, attempts to implicate such Treg as the potential source of TGF-1 by measuring the effect of depleting them on the expression level of TGF-1 or CD94-NKG2a on CD8+ T cells failed to reveal a significant effect. However, this issue requires additional study, because CD25-depleted animals still harbor a significant percentage (4%) of CD4+Foxp3+ T cells in the latent TG that may act as a source of TGF-1. These observations are consistent with the fact that >50% of Foxp3+CD4+ T cells did not express CD25 when isolated from nonlymphoid tissue such as lung (36) and would not be depleted with anti-CD25 mAb treatment. We propose that the regulatory mechanism operative in the latently infected sensory neurons functionally involves CD94-NKG2a inhibitory receptor and presumably CD4+Foxp3+ Treg cells to protect irreplaceable neurons from destruction by the immune system.
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Acknowledgments |
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Disclosures |
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Footnotes |
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1 This work was supported by National Institutes of Health and National Eye Institute Research Grants AI14981 and EYO5093. 
2 Address correspondence and reprint requests to Dr. Barry T. Rouse, Department of Microbiology, M409, Walters Life Sciences Building, University of Tennessee, Knoxville, TN 37996-0845. E-mail address: btr{at}utk.edu or ssuvas{at}utk.edu
3 Abbreviations used in this paper: TG, trigeminal ganglion; Foxp, forkhead/winged helix transcription factor; Qdm, Qa-1 determinant modifier; Treg, regulatory T; NKG2a, NK cell receptor subfamily G2a; KLRG1, killer cell lectin-like subfamily G1.
Received for publication September 15, 2005. Accepted for publication November 3, 2005.
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionDisclosuresReferences |
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gene mRNA is prominent in latently infected neurons. Science 235: 1056-1059. in controlling the expression of CD94/NKG2A receptors on CD8 T cells. Eur. J. Immunol. 35: 766-775. [Medline]. Annu. Rev. Immunol. 16: 137-161. [Medline] receptor type II (rhTGF-sRII). Cytokine 7: 389-397. [Medline]1 plays an important role in the mechanism of CD4+CD25+ regulatory T cell activity in both humans and mice. J. Immunol. 172: 834-842. suspends the killing license of anti-tumor CTLs. J. Clin. Invest. 110: 1407-1409. [Medline]-induced expression of CD94/NKG2A inhibitory receptors in human T lymphocytes. Eur. J. Immunol. 29: 23-29. [Medline]This article has been cited by other articles:
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  S. Chattopadhyay, J. O'Rourke, and R. E. Cone Implication for the CD94/NKG2A-Qa-1 system in the generation and function of ocular-induced splenic CD8+ regulatory T cells Int. Immunol., April 1, 2008; 20(4): 509 - 516. [Abstract] [Full Text] [PDF]
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J. D. Mintern, C. Guillonneau, F. R. Carbone, P. C. Doherty, and S. J. Turner Cutting Edge: Tissue-Resident Memory CTL Down-Regulate Cytolytic Molecule Expression following Virus Clearance J. Immunol., December 1, 2007; 179(11): 7220 - 7224. [Abstract] [Full Text] [PDF]
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 V. J. Cavanaugh, D. H. Raulet, and A. E. Campbell Upregulation of CD94/NKG2A receptors and Qa-1b ligand during murine cytomegalovirus infection of salivary glands J. Gen. Virol., May 1, 2007; 88(5): 1440 - 1445. [Abstract] [Full Text] [PDF]
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 J. E. Knickelbein, S. Divito, and R. L. Hendricks Modulation of CD8+ CTL Effector Function by Fibroblasts Derived from the Immunoprivileged Cornea Invest. Ophthalmol. Vis. Sci., May 1, 2007; 48(5): 2194 - 2202. [Abstract] [Full Text] [PDF]
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N. J. Robertson, J.-G. Chai, M. Millrain, D. Scott, F. Hashim, E. Manktelow, F. Lemonnier, E. Simpson, and J. Dyson Natural Regulation of Immunity to Minor Histocompatibility Antigens J. Immunol., March 15, 2007; 178(6): 3558 - 3565. [Abstract] [Full Text] [PDF]
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 G. M. G. M. Verjans, R. Q. Hintzen, J. M. van Dun, A. Poot, J. C. Milikan, J. D. Laman, A. W. Langerak, P. R. Kinchington, and A. D. M. E. Osterhaus Selective retention of herpes simplex virus-specific T cells in latently infected human trigeminal ganglia PNAS, February 27, 2007; 104(9): 3496 - 3501. [Abstract] [Full Text] [PDF]
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B. S. Sheridan, K. M. Khanna, G. M. Frank, and R. L. Hendricks Latent Virus Influences the Generation and Maintenance of CD8+ T Cell Memory J. Immunol., December 15, 2006; 177(12): 8356 - 8364. [Abstract] [Full Text] [PDF]
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 C. O. Simon, R. Holtappels, H.-M. Tervo, V. Bohm, T. Daubner, S. A. Oehrlein-Karpi, B. Kuhnapfel, A. Renzaho, D. Strand, J. Podlech, et al. CD8 T Cells Control Cytomegalovirus Latency by Epitope-Specific Sensing of Transcriptional Reactivation J. Virol., November 1, 2006; 80(21): 10436 - 10456. [Abstract] [Full Text] [PDF]
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