Differences in the ligand specificity between CD1d-restricted T cells withlimited and diverse T-cell receptor repertoire

The natural killer (NK) T-lymphocyte population consists of two subsets uti lizing a diverse and restricted T-cell receptor (TCR) repertoire, respectiv ely. Both populations have been shown to include autoreactive cells. NKT ce lls carrying restricted V alpha 14(AV14S1)J alpha 281/V beta 8.2(BV8S2A1) T CR have been shown to recognize alpha-galactosylceramide (alpha GalCer) pre sented in the context of murine CD1d. In this study we screened a set of mu rine CD1d-autoreactive T-cell hybridomas with diverse TCR for their reactiv ity with several glycosylated variants of ceramide, including alpha GalCer. These hybridomas showed a different pattern of reactivity to CD1d-expressi ng antigen-presenting cells (APC) and were not reactive with any of the tes ted variants of ceramide. A second set of hybridomas had been selected for expression of V alpha 14 and V beta 8.2 TCR chains. These cells responded t o alpha GalCer presented on CD1d, but were only weakly reactive to syngenei c splenocytes or CD1d-transfected cells. Their fine specificity in the resp onse to glycosylation variants of ceramide demonstrated a homogenous reacti vity pattern, including reactivity to alpha-galactosylsphingosine, the vari ant of alpha GalCer with truncated fatty acyl chain. These findings underli ne the differences in ligand specificity between the two subsets of CD1d-re stricted NKT cells, and demonstrate a similarity in reactivity among the hy bridomas using the V alpha 14-J alpha 281/V beta 8.2 TCR.