SELECTION OF GAMMA-DELTA-T-CELLS WITH CANONICAL T-CELL ANTIGEN RECEPTORS IN FETAL THYMUS

Two γδ T-cell subsets that are generated in the fetal thymus and selectively localize in epidermis and uterus-vagina-tongue epithelia exhibit remarkable homogeneity in their (T-cell) antigen receptors (TCR). In the present study, we show that cells expressing the canonical γδ TCR are also generated in fetal thymus organ cultures. Treatment of these cultures with anti-γδ TCR antibodies did not prevent γδ T-cell development but led to a striking increase in the frequency of noncanonical in-frame sequences. We conclude from this finding that cells expressing the canonical TCR accumulate selectively as a result of TCR-mediated positive selection in the fetal thymus.