The murine NK receptor 2B4 (CD244) exhibits inhibitory function independent of signaling lymphocytic activation molecule-associated protein expression.
2B4 (CD244) is a receptor belonging to the CD2-signaling lymphocytic activation molecule family and is found on all murine NK cells and a subset of NKT and CD8+ T cells. Murine 2B4 is expressed as two isoforms (2B4 short and 2B4 long) that arise by alternative splicing. They differ only in their cytoplasmic domains and exhibit opposing function when expressed in the RNK-16 cell line. The ligand for 2B4, CD48, is expressed on all hemopoietic cells. Previous studies have shown that treatment of NK cells with a 2B4 mAb results in increased cytotoxicity and IFN-gamma production. In this report, we used CD48+/- variants of the P815 tumor cell line and 2B4 knockout mice to show that engagement of 2B4 by its counterreceptor, CD48, expressed on target cells leads to an inhibition in NK cytotoxicity. The addition of 2B4 or CD48 mAb relieves this inhibition resulting in enhanced target cell lysis. This 2B4-mediated inhibition acts independently of signaling lymphocytic activation molecule-associated protein expression. Imaging studies show that 2B4 preferentially accumulates at the interface between NK and target cells during nonlytic events also indicative of an inhibitory receptor. This predominant inhibitory function of murine 2B4 correlates with increased 2B4 long isoform level expression over 2B4 short.
Mooney
Jill M
JM
Graduate Program in Immunology, University of Texas Southwestern Medical Center, Dallas 75390, USA. Jill.Mooney@utsouthwestern.edu
Klem
Jennifer
J
Wülfing
Christoph
C
Mijares
Lilia A
LA
Schwartzberg
Pamela L
PL
Bennett
Michael
M
Schatzle
John D
JD
D000818:Animals; D019138:Antibodies, Blocking / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D000071178:CD48 Antigen; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D003601:Cytotoxicity Tests, Immunologic; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology*; D047908:Intracellular Signaling Peptides and Proteins; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000235:genetics; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D011971:Receptors, Immunologic / Q000172:deficiency / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; D000071176:Signaling Lymphocytic Activation Molecule Family; D015854:Up-Regulation / Q000235:genetics / Q000276:immunology
D019138:Antibodies, Blocking; D015703:Antigens, CD; D000071178:CD48 Antigen; D002352:Carrier Proteins; C490007:Cd244a protein, mouse; C000604066:Cd48 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D011971:Receptors, Immunologic; C499569:Sh2d1a protein, mouse; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; D000071176:Signaling Lymphocytic Activation Molecule Family