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The Journal of Immunology, 2006, 176: 4646-4650.
Copyright © 2006 by The American Association of Immunologists

CD48 Stimulation by 2B4 (CD244)-Expressing Targets Activates Human NK Cells1

Birgitta Messmer, Philipp Eissmann, Sebastian Stark and Carsten Watzl2

Institute for Immunology, University of Heidelberg, Heidelberg, Germany


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 Disclosures
 References
 
Human NK cells can be activated by a variety of different cell surface receptors. Members of the SLAM-related receptors (SRR) are important modulators of NK cell activity. One interesting feature of the SRR is their homophilic interaction, combining receptor and ligand in the same molecule. Therefore, SRR cannot only function as activating NK cell receptors, but also as activating NK cell ligands. 2B4 (CD244) is the only SRR that does not show homophilic interaction. Instead, 2B4 is activated by binding to CD48, a GPI-anchored surface molecule that is widely expressed in the hemopoietic system. In this study, we show that 2B4 also can function as an activating NK cell ligand. 2B4-expressing target cells can efficiently stimulate NK cell cytotoxicity and IFN-{gamma} production. Using soluble receptor fusion proteins and SRR-transfected cells, we show that 2B4 does not bind to any other SRR expressed on NK cells, but only interacts with CD48. Lysis of 2B4-expressing target cells can be blocked by anti-CD48 Abs and triggering of CD48 in a redirected lysis assay can stimulate NK cell cytotoxicity. This demonstrates that 2B4 can stimulate NK cell cytotoxicity and cytokine production by interacting with NK cell expressed CD48 and adds CD48 to the growing number of activating NK cell receptors.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 Disclosures
 References
 
The activity of NK cells is regulated by a fine balance between signals from activating and inhibitory cell surface receptors (1). Inhibitory receptors for MHC class I molecules guarantee the self-tolerance of NK cells (2). NK cell activation results in cell-mediated cytotoxicity and cytokine secretion and is important for the immune response against viral infections and transformed cells (3). A variety of different surface receptors can induce NK cell activation. The natural cytotoxicity receptors NKp30, NKp44, and NKp46 and the NKG2D receptor have been described as the major NK cell activating receptors (4). Members of the signaling lymphocyte activation molecule SLAM-related receptors (SRR)3 are important in the modulation and costimulation of NK cell responses and can also regulate the function of other lymphocytes (5). The SRR expressed by all NK cells are 2B4 (CD244), NTB-A (NK-T-B cell Ag), and CS1 (CRACC). NTB-A and CS1 are their own ligands and can lead to NK cell activation by homophilic interaction (6, 7, 8). 2B4 binds to CD48 (9), a GPI-anchored Ig superfamily member, which is widely expressed in the hemopoietic system and is also present on all NK cells.

2B4 is an important modulator for the activity of NK cells and other lymphocytes (10, 11, 12). It can effectively costimulate the signals of other activating NK cell receptors (13) and can enhance the cytotoxic activity of Ag-specific T cells (14). 2B4 is expressed by human eosinophils and can activate their effector functions (15). The interaction between 2B4 and CD48 is important for the proliferation of mouse NK and T cells and is necessary for the generation of effector functions in mouse NK cells (16, 17, 18). Under certain circumstances 2B4 can even mediate the inhibition of NK cell function in mouse and human NK cells (19, 20, 21). Interestingly, 2B4 and CD48 are also expressed on multipotent hemopoietic progenitor cells and, together with other members of the SRR, are the only receptors whose expression can distinguish hemopoietic stem cells and progenitor cells (22). These findings suggest that the interaction between 2B4 and CD48 is involved in the regulation of many cellular processes in the hemopoietic system.

In this study, we show that 2B4 cannot only work as an activating NK cell receptor, but that it can also function as an activating NK cell ligand. 2B4 expression on target cells can stimulate NK cell cytotoxicity and IFN-{gamma} production through the engagement of CD48 on NK cells. This demonstrates that the 2B4-CD48 interaction can generate bidirectional signals through 2B4 and CD48.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 Disclosures
 References
 
Cells, Abs, and fusion proteins

The cells used in this study were: NK92-C1 (cultured in Alpha medium, 12.5% FCS, 12.5% horse serum, 50 µM 2-ME, 2 mM glutamine and penicillin/streptomycin); 293 (cultured in DMEM, 10% FCS, penicillin/streptomycin); BaF3 (cultured in RPMI 1640, 10% FCS, 50 mM 2-ME, penicillin/streptomycin); P815 (cultured in IMDM, 10% FCS, penicillin/streptomycin); and primary human NK cells, isolated and cultured as described (23). T cell clones were generated by limiting dilution of NK cell-depleted PBL. Clones were stimulated by autologous PBL as feeder cells in the presence of PHA and 100 U/ml IL-2 and restimulated by allogeneic PBL after 1 wk. Wells positive for growth were then expanded and tested by surface staining. BaF3 and 293 cells were stably transfected with the cDNAs for CD48, 2B4, NTB-A, CS1, or GFP using a retroviral system. The Abs used were anti-CD48 (clone 4H9; Santa Cruz Biotechnology), anti-CD48 (clone J4-57; Beckman Coulter), anti-2B4 (C1.7) (provided by G. Trinchieri, The Wistar Institute, Philadelphia, PA), goat anti-mouse IgG PE-conjugated (Jackson ImmunoResearch Laboratories), and MOPC21 (Sigma-Aldrich) as an isotype control. The monoclonal anti-NTB-A (NT-7) and anti-CRACC (CS1.4), and anti-isoleucine zipper (ILZ)-11 have been previously described (6, 24). The isoleucine fusion proteins ILZ-CD4, ILZ-2B4, ILZ-CD48, ILZ-NTB-A, and ILZ-CS1 have been generated as described previously (24).

FACS analysis

For surface staining, the cells were incubated with the indicated mAbs (10 µg/ml) or ILZ-fusion proteins (1 µg/ml) in 50 µl of FACS buffer (PBS, 2% FCS) for 20 min on ice. All washing steps were performed with cold FACS buffer. Ab-labeled cells were then stained with PE-conjugated goat anti-mouse Ab (1/200). ILZ fusion protein stained cells were incubated with an anti-ILZ-11 Ab (5 µg/ml) followed by PE-conjugated goat anti-mouse Ab.

Killing assay

Target cells were grown to mid-log phase, and 5 x 105 cells were labeled in 100 µl of CTL medium (IMDM with 10% FCS and penicillin/streptomycin) with 100 µCi 51Cr for 1 h at 37°C. Cells were washed twice in CTL medium and resuspended at 5 x 104 cells/ml in CTL medium. A total of 5000 target cells/well was used in the assay. Effector cells were resuspended in CTL medium, distributed on a V-bottom 96-well plate, and mixed with labeled target cells at different E:T ratios. Maximum release was determined by incubating target cells in 1% Triton X-100. For spontaneous release, targets were incubated without effectors in CTL medium alone. For a redirected lysis assay Abs were used at a final assay concentration of 0.5 µg/ml. For blocking experiments, Abs were used at a final assay concentration of 10 µg/ml. All samples were done in triplicates, and IL-2 was used at 100 IU/ml final concentration in the whole assay. After a 1-min centrifugation at 1000 rpm, plates were incubated for 4 h at 37°C. Supernatant was harvested and 51Cr release was measured in a gamma counter. Percentage of specific release was calculated as ((experimental release – spontaneous release)/(maximum release – spontaneous release)) x 100.

IFN-{gamma} release assay

The 96-well plates were coated with anti-ILZ-11 Ab (10 µg/ml in PBS) for 16 h at 4°C. Plates were washed with sterile PBS and incubated with ILZ-fusion proteins (5 µg/ml in PBS) for 1 h at room temperature. Plates were washed again and incubated with 1 x 105 NK cells per well. Target cells were used at 1 x 105 cells/well. All samples were done in triplicates. Plates were incubated for 20 h at 37°C and supernatants were harvested. Quantification of IFN-{gamma} was performed using a quantitative sandwich ELISA (Quantikine kit; R&D Systems) according to the manufacturer’s instructions.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 Disclosures
 References
 
To investigate the functional consequences of stimulating different SRR with their respective ligands on target cells we generated stable mouse Baf3 transfectants expressing human NTB-A, CD48, and CS1 (Fig. 1A). As a control we also generated Baf3 cells expressing 2B4 or GFP (Fig. 1A). As expected, the expression of CD48, NTB-A, or CS1 resulted in increased killing of the Baf3 cells by the human NK cell line NK92 (Fig. 1B), most likely through the stimulation of 2B4, NTB-A, or CS1, respectively. Interestingly, also the 2B4-expressing Baf3 cells were much better targets when compared with the control transfected Baf3-GFP cells (Fig. 1B). To confirm that 2B4 expression on target cells can enhance their lysis, we generated human 293 cells stably expressing 2B4 or GFP as a control (Fig. 1A). Also in this system, 2B4 expression significantly enhanced the lysis of the 293 cells (Fig. 1C). This result suggests that 2B4 can also function as an activating ligand for human NK cells.


Figure 1
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  		FIGURE 1. 2B4-expressing target cells stimulate NK cell-mediated cytotoxicity. A, Analysis of stable Baf3 and 293 transfectants. Stably transfected Baf3 or 293 cells were stained with an isotype control Ab (open histogram) or an Ab against the transfected surface receptor (black histogram). For GFP transfectants (black histogram) the fluorescence was compared with nontransfected cells (open histogram). B and C, Killing assay using NK92 cells as effectors. The indicated Baf3 (B) or 293 (C) transfectants were used as targets in a 4-h 51Cr release assay with NK92 as effector cells. The assays were repeated at least three times and representative results are shown.

 
The only known ligand for human 2B4 is CD48 (9). To confirm this interaction and to exclude the possibility that 2B4 stimulates NK cell activation by binding to another member of the SRR, we stained the 2B4-transfected Baf3 and 293 cells with different soluble ILZ receptor fusion proteins (24). Only ILZ-CD48 bound specifically to the Baf3-2B4 and 293-2B4 cells, whereas no binding of ILZ-2B4, NTB-A, or CS1 could be observed (Fig. 2A). This demonstrates that the transfected 2B4 only binds to CD48 and does not interact with 2B4, NTB-A, or CS1, which are the only SRR expressed by human NK cells. To test whether the binding of ILZ-CD48 is specific for 2B4-expressing cells we tested the binding to the different Baf3 and 293 transfectants. ILZ-CD48 only bound the Baf3-2B4 and 293-2B4 cells (Fig. 2B), confirming the specificity of this interaction. More importantly, soluble ILZ-2B4 only bound to Baf3-CD48 and 293-CD48 cells, but not to any other transfectant (Fig. 2B), demonstrating that 2B4 specifically and exclusively interacts with CD48. This suggests that the 2B4 expressed on the target cells stimulates cytotoxicity by engaging CD48 on the NK cells. CD48 is expressed by all NK cells as well as the NK92 cell line, and ILZ-2B4 can specifically bind to NK92 cells (Fig. 2C) and also to primary NK cells (data not shown).


Figure 2
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  		FIGURE 2. The 2B4 cells only interacts with CD48. A, Baf3–2B4 or 293–2B4 cells were stained with the indicated ILZ fusion proteins, followed by an anti-ILZ Ab (ILZ-11) and a PE-labeled goat anti-mouse Ab. B, The indicated cells were stained with ILZ-2B4 or ILZ-CD48 as described in A. C, NK92 cells were stained with an anti-CD48 Ab (left) or ILZ-2B4 (right). Open histogram represents control staining.

 
To prove that the interaction between 2B4 and CD48 is responsible for the enhanced killing of 2B4-expressing target cells, we tried to block the killing of 293-2B4 cells with different Abs. Two different anti-CD48 Abs were both effective in completely blocking the killing of 293-2B4 cells (Fig. 3), demonstrating that CD48 is essential for the killing of 293-2B4 targets. Also an anti-2B4 Ab significantly reduced the lysis, possibly by masking 2B4 on the target cells (Fig. 3). As the NK92 cells used in this assay are FcR-negative, binding of the anti-2B4 Ab to the 293-2B4 cells cannot induce Ab-dependent cellular cytotoxicity. 2B4 is present on the target and the NK cells. Therefore, the amount of Ab used may not be enough to completely mask 2B4 on the target cells, explaining the lack of a more complete block.


Figure 3
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  		FIGURE 3. Killing of 293–2B4 cells can be blocked by anti-CD48 Abs. 293-GFP or 293–2B4 cells were used at the indicated E:T ratio in a killing assay with the FcR-negative NK cell line NK92 in the presence of a control Ab (IgG1) or two different Abs against CD48 or an anti-2B4 Ab. One representative of three different experiments is shown.

 
These data suggest that CD48 can function as an activating NK cell receptor. To directly test this idea, we performed a redirected lysis assay using FcR-positive P815 cells as targets. Two different anti-CD48 Abs were both able to stimulate NK cell cytotoxicity when compared with an isotype control Ab (Fig. 4A). This demonstrates that engagement of CD48 can lead to NK cell cytotoxicity. To test whether the engagement of CD48 by soluble 2B4 or 2B4-expressing target cells can also stimulate cytokine release by NK cells, we incubated NK92 cells in wells coated with ILZ-2B4 or CD4 as a control, or with 2B4- or GFP-expressing Baf3 and 293 cells. Engagement of NK cells by coated ILZ-2B4 clearly induced the production of IFN-{gamma} (Fig. 4B). Also, the 2B4-expressing 293 and Baf3 cells stimulated substantially more IFN-{gamma} production than the GFP-transfected control cells (Fig. 4B). This demonstrates that engagement of NK cells by 2B4 can stimulate not only cytotoxicity, but also the production of cytokines.


Figure 4
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  		FIGURE 4. Stimulation of CD48 induces NK cell cytotoxicity and IFN-{gamma} production. A, Redirected lysis of P815 cells using NK92 cells in the presence of a control Ab (IgG1) or two different anti-CD48 Abs. A representative of three different experiments is shown. B, NK92 cells were incubated in wells coated with the indicated ILZ fusion proteins or with the indicated target cells. After 20 h, the supernatants were harvested and IFN-{gamma} was measured by ELISA. All samples were done in triplicates. Mean and SD are shown. The experiment was performed twice with similar results.

 
The experiments shown so far were performed using the NK cell line NK92. This cell line is highly cytotoxic and is thought to best resemble primary NK cells. It is also the first NK cell line used clinically (25). To investigate, whether 2B4 is also an activating ligand for nontransformed NK cells, we tested purified primary NK cells for their lysis of 293 cells expressing 2B4 or GFP as a control. The presence of 2B4 significantly enhanced the lysis of 293 cells (Fig. 5A). This demonstrates that 2B4 can also function as an activating ligand for purified primary NK cells. However, when comparing NK cells, from different donors, we observed this effect only in ~45% of the cases (6 of 13 different donors tested). In the other primary NK cells, there was no difference in cytotoxicity when comparing 2B4 with GFP-expressing 293 cells, even though the NK cells from all donors expressed comparable levels of CD48. This finding demonstrates that additional factors or receptors may play a role in the stimulation of NK cell cytotoxicity by 2B4-expressing target cells.


Figure 5
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  		FIGURE 5. The 2B4 cells can also function as an activating ligand for purified primary NK cells. A, The 293 transfectants were used as targets in a 4-h 51Cr release assay with purified human NK cells as effector cells. The assay was repeated with NK cells from 13 different donors. Six donors showed a similar activity as shown. B, T cell clones were stained with an isotype control Ab (dotted line histogram), anti-2B4 Ab (gray filled histogram), or an anti-CD3 Ab (filled histogram) and divided into 2B4-positive and -negative clones. The 2B4-positive (C) and 2B4-negative (D) T cell clones were used as targets in a 4-h 51Cr release assay with NK92 cells as effectors in the presence of a control Ab (MOPC21) or an Ab against 2B4 (C1.7). Results are representative of eight different clones from two independent donors.

 
To test whether naturally expressed 2B4 can also stimulate NK cells, we made use of the fact that a subpopulation of CD8-positive T cells express 2B4. We therefore generated T cell clones and screened them for 2B4 expression (Fig. 5B). We then compared 2B4-positive and 2B4-negative T cell clones as targets in a killing assay in the presence of a control Ab or an Ab against 2B4. As effectors we used NK92 cells because these cells lack FcRs and can therefore not mediate Ab-dependent cellular cytotoxicity. The anti-2B4 Ab reduced target cell lysis only in the case of 2B4-positive T cell clones, demonstrating that endogenously expressed 2B4 can also stimulate NK cell cytotoxicity.


   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
Disclosures
 References
 
NK cells can be activated by a variety of different surface receptors. In this study we have shown that 2B4 expression on target cells can lead to the activation of NK cells, resulting in cytotoxicity and IFN-{gamma} production. The 2B4-expressing target cells bound only soluble CD48 receptor and soluble 2B4 only interacted with CD48-expressing cells. This demonstrates the specificity of the 2B4-CD48 interaction and excludes that 2B4-expressing target cells stimulate NK cells by interacting with other members of the SRR present on NK cells, such as 2B4 itself, NTB-A, or CS1. CD48 can therefore be added to the growing list of stimulating NK cell receptors. Our data confirm a recent report by Mathew et al. (26) demonstrating that 2B4-transfected K562 cells are better killed by NK92 cells than by untransfected K562 targets.

Members of the SRR are mostly homophilic, combining receptor and ligand in the same molecule. Interactions between SRR-expressing cells can therefore generate bidirectional signals that affect both interacting cells. 2B4 is the only SRR that does not show homophilic binding but specifically interacts with CD48. This interaction was mostly viewed as unidirectional, with CD48 stimulating signals in 2B4-expressing cells. In this study we have shown that 2B4 can also function as a ligand by inducing signals in CD48-expressing cells. This demonstrates that the CD48–2B4 interaction is also bidirectional, by inducing signals through 2B4 and CD48.

Where is 2B4 expressed? In humans, expression can be found on all NK cells, {gamma}{delta} T cells, a subset of CD8-positive T cells, monocytes, basophils, and on eosinophils (12, 15, 27). 2B4 is also expressed on multipotent hemopoietic progenitor cells (22). NK cells may be stimulated through CD48 upon encounter of such 2B4-positive cells, as evident from our results with 2B4-positive T cell clones. The engagement of 2B4 and CD48 during interaction among NK cells can lead to a cytotoxic response when MHC class I molecules are blocked (S. Stark and C. Watzl, unpublished observation). A recent report demonstrated that the interaction between 2B4 and CD48 is important for the generation of effector functions in mouse NK cells (16). In these cases, 2B4 may not only be important as a receptor, but could also function as a ligand for CD48, whose signals could be responsible for the observed effect. The 2B4-CD48 interaction among T cells or during the interaction between T cells and NK cells can enhance T cell cytotoxicity and proliferation (10, 14, 17, 18). There is also evidence that during these interactions, 2B4 can function as a ligand for CD48 (14, 17, 18). This demonstrates that the signals of both 2B4 and CD48 can regulate the function of different immune cells. The recent description of 2B4 and CD48 on hemopoietic progenitor cells (22) suggests that the signals of those receptors could also be important for the development of lymphocytes.

CD48 is a GPI-anchored surface molecule. How can the engagement of this receptor generate intracellular signaling events? GPI-anchored surface molecules are enriched in specialized membrane domains called lipid rafts (28). Rafts have been shown to be important for the activation of NK cells and other lymphocytes (23, 29, 30, 31). The clustering of rafts by the engagement of CD48 could be sufficient to generate a positive signal leading to NK cell activation. A similar activity of CD48 has been described for the stimulation of T cells (32). The fact that not all primary NK cells can be stimulated by 2B4-expressing target cells suggests that additional cofactors may be necessary for CD48-mediated NK cell activation. We have not yet found any significant difference between NK cells that can be stimulated by 2B4-expressing target cells and NK cells that cannot. Finding the reason for this difference and studying the signal transduction of CD48 in future studies will give us a better understanding of the molecular mechanism of the 2B4-CD48 interaction.


   Disclosures
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Disclosures
References
 
The authors have no financial conflict of interest.


   Footnotes
 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

1 This work was supported by the Deutsche Forschungsgemeinschaft Grant SFB405 A9. Back

2 Address correspondence and reprint requests to Dr. Carsten Watzl, Institute for Immunology, Im Neuenheimer Feld 305, University of Heidelberg, 69120 Heidelberg, Germany. E-mail address: carsten.watzl{at}urz.uni-heidelberg.de Back

3 Abbreviations used in this paper: SRR, SLAM-related receptor; ILZ, isoleucine zipper. Back

Received for publication July 12, 2005. Accepted for publication February 3, 2006.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Disclosures
 References
 

  1. Lanier, L. L.. 2005. NK cell recognition. Annu. Rev. Immunol. 23: 225-274. [Medline]
  2. Long, E. O., D. F. Barber, D. N. Burshtyn, M. Faure, M. Peterson, S. Rajagopalan, V. Renard, M. Sandusky, C. C. Stebbins, N. Wagtmann, C. Watzl. 2001. Inhibition of natural killer cell activation signals by killer cell immunoglobulin-like receptors (CD158). Immunol. Rev. 181: 223-233. [Medline]
  3. Hamerman, J. A., K. Ogasawara, L. L. Lanier. 2005. NK cells in innate immunity. Curr. Opin. Immunol. 17: 29-35. [Medline]
  4. Moretta, L., A. Moretta. 2004. Unravelling natural killer cell function: triggering and inhibitory human NK receptors. EMBO J. 23: 255-259. [Medline]
  5. Veillette, A., S. Latour. 2003. The SLAM family of immune-cell receptors. Curr. Opin. Immunol. 15: 277-285. [Medline]
  6. Flaig, R. M., S. Stark, C. Watzl. 2004. Cutting edge: NTB-A activates NK cells via homophilic interaction. J. Immunol. 172: 6524-6527. [Abstract/Free Full Text]
  7. Falco, M., E. Marcenaro, E. Romeo, F. Bellora, D. Marras, F. Vély, G. Ferracci, L. Moretta, A. Moretta, C. Bottino. 2004. Homophilic interaction of NTBA, a member of the CD2 molecular family: induction of cytotoxicity and cytokine release in human NK cells. Eur. J. Immunol. 34: 1663-1672. [Medline]
  8. Kumaresan, P. R., W. C. Lai, S. S. Chuang, M. Bennett, P. A. Mathew. 2002. CS1, a novel member of the CD2 family, is homophilic and regulates NK cell function. Mol. Immunol. 39: 1-8. [Medline]
  9. Brown, M. H., K. Boles, P. A. van der Merwe, V. Kumar, P. A. Mathew, A. N. Barclay. 1998. 2B4, the natural killer and T cell immunoglobulin superfamily surface protein, is a ligand for CD48. J. Exp. Med. 188: 2083-2090. [Abstract/Free Full Text]
  10. Assarsson, E., T. Kambayashi, C. M. Persson, H. G. Ljunggren, B. J. Chambers. 2005. 2B4 co-stimulation: NK cells and their control of adaptive immune responses. Mol. Immunol. 42: 419-423. [Medline]
  11. McNerney, M. E., K. M. Lee, V. Kumar. 2005. 2B4 (CD244) is a non-MHC binding receptor with multiple functions on natural killer cells and CD8+ T cells. Mol. Immunol. 42: 489-494. [Medline]
  12. Boles, K. S., S. E. Stepp, M. Bennett, V. Kumar, P. A. Mathew. 2001. 2B4 (CD244) and CS1: novel members of the CD2 subset of the immunoglobulin superfamily molecules expressed on natural killer cells and other leukocytes. Immunol. Rev. 181: 234-249. [Medline]
  13. Sivori, S., S. Parolini, M. Falco, E. Marcenaro, R. Biassoni, C. Bottino, L. Moretta, A. Moretta. 2000. 2B4 functions as a co-receptor in human NK cell activation. Eur. J. Immunol. 30: 787-793. [Medline]
  14. Lee, K. M., S. Bhawan, T. Majima, H. Wei, M. I. Nishimura, H. Yagita, V. Kumar. 2003. Cutting edge: the NK cell receptor 2B4 augments antigen-specific T cell cytotoxicity through CD48 ligation on neighboring T cells. J. Immunol. 170: 4881-4885. [Abstract/Free Full Text]
  15. Munitz, A., I. Bachelet, S. Fraenkel, G. Katz, O. Mandelboim, H.-U. Simon, L. Moretta, M. Colonna, F. Levi-Schaffer. 2005. 2B4 (CD244) is expressed and functional on human eosinophils. J. Immunol. 174: 110-118. [Abstract/Free Full Text]
  16. Lee, K.-M., J. P. Forman, M. E. McNerney, S. Stepp, S. Kuppireddi, D. Guzior, Y. E. Latchman, M. H. Sayegh, H. Yagita, C.-K. Park, et al 2005. Requirement of homotypic NK cell interactions through 2B4 (CD244)/CD48 in the generation of NK effector functions. Blood : 10.1182/blood-2005-01-0185..
  17. Assarsson, E., T. Kambayashi, J. D. Schatzle, S. O. Cramer, A. von Bonin, P. E. Jensen, H. G. Ljunggren, B. J. Chambers. 2004. NK cells stimulate proliferation of T and NK cells through 2B4/CD48 interactions. J. Immunol. 173: 174-180. [Abstract/Free Full Text]
  18. Kambayashi, T., E. Assarsson, B. J. Chambers, H.-G. Ljunggren. 2001. Cutting edge: regulation of CD8+ T cell proliferation by 2B4/CD48 interactions. J. Immunol. 167: 6706-6710. [Abstract/Free Full Text]
  19. Kumar, V., M. E. McNerney. 2005. A new self: MHC-class-I-independent natural-killer-cell self-tolerance. Nat. Rev. Immunol. 5: 363-374. [Medline]
  20. Eissmann, P., L. Beauchamp, J. Wooters, J. C. Tilton, E. O. Long, C. Watzl. 2005. Molecular basis for positive and negative signaling by the natural killer cell receptor 2B4 (CD244). Blood 105: 4722-4729. [Abstract/Free Full Text]
  21. Sivori, S., M. Falco, E. Marcenaro, S. Parolini, R. Biassoni, C. Bottino, L. Moretta, A. Moretta. 2002. Early expression of triggering receptors and regulatory role of 2B4 in human natural killer cell precursors undergoing in vitro differentiation. Proc. Natl. Acad. Sci. USA 99: 4526-4531. [Abstract/Free Full Text]
  22. Kiel, M. J., O. H. Yilmaz, T. Iwashita, O. H. Yilmaz, C. Terhorst, S. J. Morrison. 2005. SLAM family receptors distinguish hematopoietic stem and progenitor cells and reveal endothelial niches for stem cells. Cell 121: 1109-1121. [Medline]
  23. Watzl, C., E. O. Long. 2003. Natural killer cell inhibitory receptors block actin cytoskeleton-dependent recruitment of 2B4 (CD244) to lipid rafts. J. Exp. Med. 197: 77-85. [Abstract/Free Full Text]
  24. Stark, S., R. M. Flaig, M. Sandusky, C. Watzl. 2005. The use of trimeric isoleucine-zipper fusion proteins to study surface-receptor-ligand interactions in natural killer cells. J. Immunol. Methods 296: 149-158. [Medline]
  25. Tonn, T., S. Becker, R. Esser, D. Schwabe, E. Seifried. 2001. Cellular immunotherapy of malignancies using the clonal natural killer cell line NK-92. J. Hematother. Stem Cell Res. 10: 535-544. [Medline]
  26. Mathew, S. O., P. R. Kumaresan, J. K. Lee, V. T. Huynh, P. A. Mathew. 2005. 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. 175: 1005-1013. [Abstract/Free Full Text]
  27. Nakajima, H., M. Colonna. 2000. 2B4: an NK cell activating receptor with unique specificity and signal transduction mechanism. Hum. Immunol. 61: 39-43. [Medline]
  28. Harder, T., K. Simons. 1997. Caveolae, DIGs, and the dynamics of sphingolipid-cholesterol microdomains. Curr. Opin. Cell Biol. 9: 534-542. [Medline]
  29. Dykstra, M., A. Cherukuri, H. W. Sohn, S. J. Tzeng, S. K. Pierce. 2003. Location is everything: lipid rafts and immune cell signaling. Annu. Rev. Immunol. 21: 457-481. [Medline]
  30. Lou, Z., D. Jevremovic, D. D. Billadeau, P. J. Leibson. 2000. A balance between positive and negative signals in cytotoxic lymphocytes regulates the polarization of lipid rafts during the development of cell-mediated killing. J. Exp. Med. 191: 347-354. [Abstract/Free Full Text]
  31. Fassett, M. S., D. M. Davis, M. M. Valter, G. B. Cohen, J. L. Strominger. 2001. Signaling at the inhibitory natural killer cell immune synapse regulates lipid raft polarization but not class I MHC clustering. Proc. Natl. Acad. Sci. USA 98: 14547-14552. [Abstract/Free Full Text]
  32. Moran, M., M. C. Miceli. 1998. Engagement of GPI-linked CD48 contributes to TCR signals and cytoskeletal reorganization: a role for lipid rafts in T cell activation. Immunity 9: 787-796. [Medline]



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