T-CELL RECEPTOR V-ALPHA AND V-BETA GENE USAGE BY TUMOR-INFILTRATING LYMPHOCYTES IN ORAL SQUAMOUS-CELL CARCINOMA

Oral squamous cell carcinomas (SCC) are often infiltrated by a large n umber of T lymphocytes. To clarify the nature of the tumour-infiltrati ng lymphocytes (TIL), we examined T cell receptor (TCR) V alpha and V beta gene usage by TIL and peripheral blood mononuclear cells (PBMC) o btained from 10 patients with oral SCC. We obtained RNA from TIL and P BMC, synthesized complementary DNA, and used the polymerase chain reac tion (PCR) method with a panel of primers specific for the V gene segm ent subfamily (V alpha 1-18/V beta 1-20). We thus found that TIL showe d more restricted usage of V beta gene families in contrast to PBMC of the same patients while two unique V beta gene (V beta 6 and V beta 5 .2) segment transcripts were overexpressed in the TIL of more than hal f of the patients. On the other hand, no major difference was observed in the V alpha gene usage between the TIL and PBMC of most patients. To characterize these T cell subpopulations with unique V beta gene se gment transcripts further, we sequenced the complementarity-determinin g region 3 in V beta 6-C beta and V beta 5.2-C beta PCR products deriv ed from TIL and PBMC of two selected patients in each case. Although n o usage of the conserved amino acid sequence by TIL was detected, the frequent use of V beta 6/J beta 1.1 in one patient and the V beta 6/J beta 2.7 gene segments in another patient was observed. Regarding the V beta 5.2 transcripts, obtained from the other two patients, no prefe rential usage of specific J beta gene segments by TIL was observed. Th ese results suggest that the unique T cell populations are amplified i n patients with oral SCC, possibly as a consequence of an in situ immu ne reaction.