CD48 may serve as an accessory molecule for the activation of a subset of human gamma/delta T cells.
To further assess the role of CD48 in the interaction of human gamma/delta T cells with their specific target, we generated two series of alloreactive clones, L and K. These clones express a V1-D-J1-C delta chain associated to V3-J2-C2 (L) or V2-J2-C2 (K) gamma chain. Functionally they were CTLs able to lyse the sensitizing B-cell line E418. The cytotoxicity of the L and K clones toward E418 was inhibited by anti-CD48 mAb. That of the L clones was also inhibited by anti-HLA class I mAbs. Variation in L and K lysis profile was observed against a panel of CD48+ targets, further strengthening the argument that they display distinct specificities and suggesting that they do not recognize CD48. Heterogeneity in TCR gene segment usage, MHC-dependent recognition of E418 by the L clones, and resistance of some CD48+ targets strongly suggest that CD48 itself does not interact with L and K TCR. Transfection of CHO cells with CD48 induced killing by the K clones. This killing was inhibited by anti-CD48 mAbs. Taking into account the recent reports on CD48 as an accessory molecule, our results suggest that by binding to CD2 (and/or an unknown ligand), CD48 may serve to strengthen E/T interaction and may contribute to the activation of a minor subset of gamma/delta T cells.
Flament
C
C
Laboratory of Cellular Immunology, INSERM U 333, Institute Gustave Roussy, Villejuif, France.
Bellagha
K
K
Rosenthal-Allieri
A
A
Chouaib
S
S
Mami-Chouaib
F
F
D000595:Amino Acid Sequence; D015703:Antigens, CD / Q000276:immunology*; D001483:Base Sequence; D000071178:CD48 Antigen; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D008969:Molecular Sequence Data; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology*; D015398:Signal Transduction / Q000276:immunology*; D016176:T-Lymphocyte Subsets / Q000276:immunology*
D015703:Antigens, CD; D000071178:CD48 Antigen; C000604065:CD48 protein, human; D016692:Receptors, Antigen, T-Cell, gamma-delta