T-CELL RECEPTOR (TCR) BETA-CHAIN HOMODIMERS ON THE SURFACE OF IMMATURE BUT NOT MATURE ALPHA-CHAIN, GAMMA-CHAIN, DELTA-CHAIN DEFICIENT T-CELL LINES

Transfected T cell receptor (TCR) beta-chain genes are expressed as homodimers on the surface of immature (Sci/ET27F) but not on mature (58-alpha--beta-) T cell lines which lack TCR-alpha, gamma and beta-chains. The homodimer on Sci/ET27F cells is tightly bound to CD3-delta and CD3-epsilon while the association with CD3-gamma and CD3-zeta proteins is rather weak. Crosslinking of the TCR-beta homodimers resulted in a strong and rapid calcium flux. In 58-alpha--beta- T cells the beta-TCR chain could be easily visualized intracellularly but was not transported to the cell surface. The Scid cell lines considerably facilitate the molecular analysis of early differentiation events in the thymus which are likely to be regulated by the beta-TCR homodimer.