|
|
||||||||
Cutting Edge |

*
Microbiology and Tumor Biology Center, Karolinska Institutet, Stockholm, Sweden; and
Center for Infectious Medicine, Department of Medicine, Karolinska Institutet, Huddinge University Hospital, Stockholm, Sweden
| Abstract |
|---|
|
|
|---|
| Introduction |
|---|
|
|
|---|

+ T cells
and CD8+ T cells (1, 2, 3, 4). Most of the
information available on 2B4 comes from studies of NK cells.
Cross-linking of 2B4 on IL-2-activated NK cells leads to stimulation of
lytic activity (1, 4, 5), IFN-
secretion
(1), and granule exocytosis (6). The
biological function of 2B4 on CD8+ T cells
remains largely unclear.
2B4+CD8+ T cells have been
associated with non-MHC-restricted cytotoxicity (6), but
cross-linking of 2B4 on CD8+ T cells does not
trigger redirected lysis of FcR-expressing targets, cytokine
production, or proliferation (4). To date, the only known 2B4-binding molecule is CD48. Binding studies have shown that CD48 has a 510 times stronger affinity for 2B4 than for CD2 (7, 8). Anti-CD48 Abs have been found to inhibit activation of CD4+ and CD8+ T cells (9, 10). Whereas CD2-/- mice are phenotypically similar to wild-type mice (11), T cells from CD48-/- mice show a severe reduction in proliferation and IL-2 production in response to lectins, anti-CD3 Ab, and alloantigen (8, 12). The relatively normal phenotype of the CD2-/- mice suggests that CD48-binding ligands other than CD2 may compensate for the absence of CD2.
In this report, we demonstrate that 2B4 is associated with an activation/memory phenotype of CD8+ T cells. Furthermore, the results suggest that 2B4 on activated/memory T cells serves as a ligand for CD48, and by its ability to interact with CD48 provides costimulatory-like function for neighboring T cells.
| Materials and Methods |
|---|
|
|
|---|
Adult C57BL/6 (B6) and TCR-transgenic (Tg)4 (F5) mice specific for an influenza nucleoprotein epitope, ASNENMDAM, presented on H-2Db (13) were bred at the Microbiology and Tumor Biology Center, Karolinska Institutet (Stockholm, Sweden). Animal care was in accordance with national and institutional guidelines.
Reagents
All chemicals were purchased from Sigma-Aldrich (St. Louis, MO) unless otherwise specified. The influenza virus nucleoprotein-derived peptide (nucleoprotein (NP)366374), ASNENMDAM, was purchased from Research Genetics (Huntsville, AL). All Ab used were purchased from BD PharMingen (San Diego, CA) except for anti-CD2 (Southern Biotechnology Associates, Birmingham, AL).
Preparation of CD8+ T cells
CD8
+ cells were purified from spleens
of mice using the MACS separation system (Miltenyi Biotec, Bergisch
Gladbach, Germany) according to the manufacturers guidelines and
resuspended in complete medium (
MEM, 10 mM HEPES, 2 x
10-5 M 2-ME, 10% FCS, 100 U/ml penicillin, 100
U/ml streptomycin; Life Technologies, Paisley, U.K.) plus
recombinant human IL-2 (1000 U/ml; PeproTech, Rocky Hill, NJ) for 6
days. FACS analysis of these cells demonstrated that only
CD8+TCR+ cells were present
in these cultures. Purification of CD8+ T cells
from influenza-infected mice has been described previously
(14).
RT-PCR
2B4 transcripts were detected using RNA from naive or activated
CD8+ T cells by RT-PCR using the following
primers: 2B4 short transcripts were detected using
5'-ACTGTTTTTGTCCTGCTTGGTG and 3'-AGGAAACTGGTGGAGAAGAAAA (Cybergene,
Stockholm, Sweden) encompassing nt 573-1093 of murine 2B4 (m2B4)
short. m2B4 long transcripts were detected using
5'-TGGAAGAAGACAGAACAGGG and 3'-TGGAATCAGAAGGCTTGCAC encompassing nt
283-1136 of m2B4 long. cDNA quality was confirmed by amplification of a
-actin gene fragment.
Flow cytometry
Following FcR-block, cells were stained with the specified Ab or its isotype control or Db-NP366-RED670 tetramer (14, 15). The fluorescence intensity was measured on a FACScan flow cytometer (BD Biosciences, Mountain View, CA) and analyzed using CellQuest computer software (BD Biosciences).
CD8+ T cell proliferation assays
Bone marrow-derived dendritic cells (DC) were pulsed with ASNENMDAM peptide overnight at 37°C and seeded at 2 x 104 cells/well in U-bottom 96-well plates. A total of 3 x 104 TCR-Tg CD8+ T cells (naive or IL-2-activated) or TCR-Tg lymphokine-activated T (LAT) cells (FACS sorted into NK1.1+ or NK1.1-) were added to each well with the indicated azide-free Ab. When B6 LAT cells were mixed with naive TCR-Tg CD8+ T cells, 4 x 104 B6 LAT cells (sorted into NK1.1+ or NK1.1-) were added with 3 x 104 naive TCR-Tg CD8+ T cells to each well. In APC-free experiments, plates were coated overnight at 4°C with purified Db-NP366 monomers (14, 15) at various concentrations with anti-CD28 Ab (10 µg/ml) in PBS. TCR-Tg LAT cells (3 x 104) were added to each well. In cytokine-induced proliferation assays, 3 x 104 B6 CD8+ T cells (naive or IL-2-activated) and TCR-Tg LAT cells (sorted into NK1.1+ or NK1.1-) were stimulated with IL-2 (1000 U/ml). All proliferation assays were for 72 h except the naive B6 CD8+ T cell cytokine-induced proliferation assay, which was for 120 h. [3H]Thymidine (1 µCi/ml) was added for the last 18 h of all assays. The plates were harvested on glass fiber filters (Wallac, Turku, Finland) and analyzed in a beta-scintillation counter (Wallac).
| Results and Discussion |
|---|
|
|
|---|
One to 2% of all splenic CD8+ T cells from
normal uninfected mice express 2B4. In the present study, we show that
activation by IL-2, IL-4, and IL-15 induced expression of 2B4 on
CD8+ T cells (Fig. 1
A and data not shown).
CD8+2B4+ T cells were
predominantly CD44high and
CD62Llow (data not shown), in line with
recent findings showing that expression of NK cell receptors on
CD8+ T cells is associated with a memory
phenotype (16, 17). Alternative splicing of the 2B4 mRNA
has been shown to give rise to two different polypeptides, 2B4 long and
2B4 short, differing in their cytoplasmic tails while having identical
extracellular domains (18, 19). As shown in Fig. 1
B, both the short and long forms of 2B4 were equally
up-regulated in CD8+ T cells after stimulation
with IL-2. Taken together, the data indicated that expression of 2B4
was increased in IL-2-activated CD8+ T cells both
at the cell surface and at the transcriptional level. 2B4 expression
was also observed on CD8+ T cells on day 10
post-influenza infection (peak of infection). Five to 10% of all
CD8+ T cells in the lungs of infected mice
expressed 2B4 compared with 12% in untreated mice (Fig. 1
C). The expression of 2B4 on virus-specific T cells was
confirmed using tetramers of MHC class I molecules refolded with an
influenza nucleoprotein epitope
(Db-NP366) (Fig. 1
C). Although 2B4 was observed also on
tetramer- T cells, this could be related to the
other CD8+2B4+ T cells
recognizing other flu epitopes, or bystander activation, or
both.
|
The effect of anti-2B4 Ab on the proliferation of
CD8+ T cells was examined using
CD8+ T cells from mice transgenic for a TCR
specific for an influenza nucleoprotein epitope. The Ag-specific
response of purified naive TCR-Tg CD8+ T cells
was compared with that of TCR-Tg CD8+ T cells
which were first cultured in IL-2 for 6 days (hereafter denoted as CD8
LAT cells). In response to peptide-pulsed DCs, anti-2B4 Ab had no
effect on the proliferation of naive CD8+ T cells
(Fig. 2
A). However, using
TCR-Tg LAT cells, the proliferative response to peptide-pulsed DCs was
significantly diminished by anti-2B4 Ab compared with isotype
control Ab (Fig. 2
B).
|
45 and
20% reduction in the
Ag-specific proliferation of naive TCR-Tg CD8+ T
cells at peptide concentrations of 0.01 µM and 0.1 µM, respectively
(Fig. 2
45%) in CD8
LAT cell proliferation at all peptide concentrations. Interestingly,
the proliferation of CD8 LAT cells could not be further inhibited by
anti-2B4 Ab in the presence of anti-CD48 Ab, suggesting that
the effects of anti-2B4 Ab were mediated through blocking of the
2B4/CD48 interaction (Fig. 2
It has recently been suggested that the proliferation of memory T cells
is MHC independent and probably regulated by cytokines
(20). Because
CD8+2B4+ T cells in normal
mice were primarily of memory phenotype, we examined whether 2B4 also
played a role in the cytokine-induced proliferation of
CD8+ T cells. In line with the above
observations, a 4050% reduction in proliferation of naive B6
CD8+ T cells was observed with anti-CD2 or
anti-CD48 Ab, whereas no inhibition in proliferation was seen with
anti-2B4 Ab in response to IL-2 (Fig. 2
D). However, a
20% decrease in the IL-2-stimulated proliferation of B6 CD8 LAT cells
was observed in the presence of anti-2B4 or anti-CD48 Ab but
not anti-CD2 Ab (Fig. 2
D). Furthermore, taking advantage
of the fact that NK1.1 is coexpressed with 2B4 (data not shown), B6 CD8
LAT cells were sorted into NK1.1+ and
NK1.1- subsets. The addition of anti-2B4 or
anti-CD48 Abs to NK1.1+ CD8 LAT cells
resulted in an
40% attenuation of the IL-2-induced proliferation
while no effect was observed by the addition of the same Ab to
NK1.1- CD8 LAT cells (Fig. 2
D). Taken
together, these results suggested that non-MHC-restricted routes of T
cell proliferation can also be regulated by 2B4/CD48 interactions and
that such interactions may be involved in the propagation of memory T
cells.
The 2B4/CD48 interaction takes place between CD8+ T cells
Initially, we believed that the 2B4/CD48 interaction took place
between the APC and T cell, because others have reported that 2B4
cross-linking does not directly activate CD8+ T
cells and 2B4 was presumed to function as an adhesion molecule for T
cells to APCs (4, 21). However, as observed from the
inhibition of IL-2-induced proliferation of CD8 LAT cells by
anti-2B4 Ab, it was apparent that the 2B4/CD48 interaction did not
require APCs. Moreover, we found that both anti-2B4 and
anti-CD48 Ab inhibited the Ag-specific proliferation of CD8 LAT
cells in the absence of APCs where proliferation was induced by
cross-linking of the TCR using purified MHC class I-peptide complexes
(Fig. 3
A). These data
suggested that the 2B4/CD48 interaction does not necessarily take place
at the T cell/APC interface, but can also occur between neighboring
CD8+ T cells.
|
This suggested that the 2B4 expression on nonspecific
CD8+ T cells (B6 CD8 LAT cells in this case)
affects the proliferation of neighboring naive
2B4- Ag-specific CD8+ T
cells (TCR-Tg CD8+ T cells), because the B6 CD8
LAT cells did not proliferate in response to specific Ag (Fig. 3
, C and D). Furthermore, anti-2B4 Ab had no
effect on the proliferation of T cell/DC cultures when the B6 CD8 LAT
cells were separated from the naive TCR-Tg CD8+ T
cells by a cell-impermeable porous membrane, indicating that cell-cell
contact was required (data not shown). Taken together, these results
strongly suggest that 2B4 functions as a ligand for an activating
receptor on CD8+ T cells, most likely CD48,
rather than being an activating receptor itself. Although CD48 is a
GPI-anchored receptor and lacks intracytoplasmic domains, it has been
shown to be physically associated to G proteins (22) or to
the SRC family member of tyrosine kinases in glycolipid-enriched
microdomains of the cell membrane (23). Thus, it is not
surprising that a signal is transduced by CD48 upon ligation with 2B4
and can affect CD8+ T cell proliferation.
However, exactly what signals lead to the enhancement of proliferation
by 2B4/CD48 interactions is an issue that remains to be
established.
Concluding remarks
In summary, we have shown that 2B4 plays a significant role in the Ag-specific and cytokine-induced proliferation of CD8+ T cells. Although only a small proportion of CD8+ T cells normally express 2B4 in the mouse, this molecule may play a significant role in the propagation of T cells through interaction with CD48. We speculate that 2B4 could provide costimulatory signals necessary for the survival of memory T cells in response to low levels of Ag or cytokines.
| Acknowledgments |
|---|
2-microglobulin construct and Dr. D.
Kioussis for the TCR-Tg (F5 transgenic) mice. We also thank
members of the H.-G. Ljunggren laboratory for fruitful
discussions. | Footnotes |
|---|
2 T.K. and E.A. contributed equally to this study. ![]()
3 Address correspondence and reprint requests to Dr. Hans-Gustaf Ljunggren, Microbiology and Tumor Biology Center, Karolinska Institutet, 171 77 Stockholm, Sweden. E-mail address: hans-gustaf.ljunggren{at}mtc.ki.se ![]()
4 Abbreviations used in this paper: Tg, transgenic; DC, dendritic cell; LAT cell, lymphokine-activated T cell; NP, nucleoprotein; m2B4, murine 2B4. ![]()
Received for publication June 1, 2001. Accepted for publication October 25, 2001.
| References |
|---|
|
|
|---|
subunits in lymphocytes. Proc. Natl. Acad. Sci. USA 93:6053.This article has been cited by other articles:
![]() |
N. G. Clarkson, S. J. Simmonds, M. J. Puklavec, and M. H. Brown Direct and Indirect Interactions of the Cytoplasmic Region of CD244 (2B4) in Mice and Humans with FYN Kinase J. Biol. Chem., August 31, 2007; 282(35): 25385 - 25394. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Munitz, I. Bachelet, F. D. Finkelman, M. E. Rothenberg, and F. Levi-Schaffer CD48 Is Critically Involved in Allergic Eosinophilic Airway Inflammation Am. J. Respir. Crit. Care Med., May 1, 2007; 175(9): 911 - 918. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Kubota A novel functional T cell hybridoma recognizes macrophage cell death induced by bacteria: a possible role for innate lymphocytes in bacterial infection. J. Immunol., June 15, 2006; 176(12): 7576 - 7588. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Messmer, P. Eissmann, S. Stark, and C. Watzl CD48 Stimulation by 2B4 (CD244)-Expressing Targets Activates Human NK Cells. J. Immunol., April 15, 2006; 176(8): 4646 - 4650. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Bhat, P. Eissmann, J. Endt, S. Hoffmann, and C. Watzl Fine-tuning of immune responses by SLAM-related receptors J. Leukoc. Biol., March 1, 2006; 79(3): 417 - 424. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Stark and C. Watzl 2B4 (CD244), NTB-A and CRACC (CS1) stimulate cytotoxicity but no proliferation in human NK cells Int. Immunol., February 1, 2006; 18(2): 241 - 247. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Morandi, R. Costa, M. Falco, S. Parolini, A. De Maria, G. Ratto, M. C. Mingari, G. Melioli, A. Moretta, and G. Ferlazzo Distinctive Lack of CD48 Expression in Subsets of Human Dendritic Cells Tunes NK Cell Activation J. Immunol., September 15, 2005; 175(6): 3690 - 3697. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Assarsson, T. Kambayashi, C. M. Persson, B. J. Chambers, and H.-G. Ljunggren 2B4/CD48-Mediated Regulation of Lymphocyte Activation and Function J. Immunol., August 15, 2005; 175(4): 2045 - 2049. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. O. Mathew, P. R. Kumaresan, J. K. Lee, V. T. Huynh, and P. A. Mathew Mutational Analysis of the Human 2B4 (CD244)/CD48 Interaction: Lys68 and Glu70 in the V Domain of 2B4 Are Critical for CD48 Binding and Functional Activation of NK Cells J. Immunol., July 15, 2005; 175(2): 1005 - 1013. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Eissmann, L. Beauchamp, J. Wooters, J. C. Tilton, E. O. Long, and C. Watzl Molecular basis for positive and negative signaling by the natural killer cell receptor 2B4 (CD244) Blood, June 15, 2005; 105(12): 4722 - 4729. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. V. Vaidya, S. E. Stepp, M. E. McNerney, J.-K. Lee, M. Bennett, K.-M. Lee, C. L. Stewart, V. Kumar, and P. A. Mathew Targeted Disruption of the 2B4 Gene in Mice Reveals an In Vivo Role of 2B4 (CD244) in the Rejection of B16 Melanoma Cells J. Immunol., January 15, 2005; 174(2): 800 - 807. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Assarsson, T. Kambayashi, J. D. Schatzle, S. O. Cramer, A. von Bonin, P. E. Jensen, H.-G. Ljunggren, and B. J. Chambers NK Cells Stimulate Proliferation of T and NK Cells through 2B4/CD48 Interactions J. Immunol., July 1, 2004; 173(1): 174 - 180. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. D. Vu, F. Amanullah, Y. Li, G. Demirci, M. H. Sayegh, and X. C. Li Different Costimulatory and Growth Factor Requirements for CD4+ and CD8+ T Cell-Mediated Rejection J. Immunol., July 1, 2004; 173(1): 214 - 221. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Chen, F. Relouzat, R. Roncagalli, A. Aoukaty, R. Tan, S. Latour, and A. Veillette Molecular Dissection of 2B4 Signaling: Implications for Signal Transduction by SLAM-Related Receptors Mol. Cell. Biol., June 15, 2004; 24(12): 5144 - 5156. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Dhanji and H.-S. Teh IL-2-Activated CD8+CD44high Cells Express Both Adaptive and Innate Immune System Receptors and Demonstrate Specificity for Syngeneic Tumor Cells J. Immunol., October 1, 2003; 171(7): 3442 - 3450. [Abstract] [Full Text] [PDF] |
||||
![]() |
K.-M. Lee, S. Bhawan, T. Majima, H. Wei, M. I. Nishimura, H. Yagita, and V. Kumar Cutting Edge: The NK Cell Receptor 2B4 Augments Antigen-Specific T Cell Cytotoxicity Through CD48 Ligation on Neighboring T Cells J. Immunol., May 15, 2003; 170(10): 4881 - 4885. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Kambayashi, E. Assarsson, A. E. Lukacher, H.-G. Ljunggren, and P. E. Jensen Memory CD8+ T Cells Provide an Early Source of IFN-{gamma} J. Immunol., March 1, 2003; 170(5): 2399 - 2408. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Murakami, H. Kosaka, Y. Maeda, J.-i. Nishimura, N. Inoue, K. Ohishi, M. Okabe, J. Takeda, and T. Kinoshita Inefficient response of T lymphocytes to glycosylphosphatidylinositol anchor-negative cells: implications for paroxysmal nocturnal hemoglobinuria Blood, December 1, 2002; 100(12): 4116 - 4122. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Klem, P. C. Verrett, V. Kumar, and J. D. Schatzle 2B4 Is Constitutively Associated with Linker for the Activation of T Cells in Glycolipid-Enriched Microdomains: Properties Required for 2B4 Lytic Function J. Immunol., July 1, 2002; 169(1): 55 - 62. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. Demirci, W. Gao, X. X. Zheng, T. R. Malek, T. B. Strom, and X. C. Li On CD28/CD40 Ligand Costimulation, Common {gamma}-Chain Signals, and the Alloimmune Response J. Immunol., May 1, 2002; 168(9): 4382 - 4390. [Abstract] [Full Text] [PDF] |
||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |