SURFACE EXPRESSION OF A T-CELL RECEPTOR BETA (TCR-BETA) CHAIN IN THE ABSENCE OF TCR-ALPHA, TCR-DELTA, AND TCR-GAMMA PROTEINS

The antigen receptor expressed by mature T cells has been described as a disulfide-linked alpha/beta or gamma/delta heterodimer noncovalently associated with CD3, a complex of transmembrane proteins that communicates signals from the T cell receptor (TCR) to the cell interior. Studies suggest that all component chains must assemble intracellularly before surface expression can be achieved. We described, however, a CD4+/CD8+ transformed murine thymocyte, KKF, that expresses surface TCR-beta chains in the absence of gamma, delta, and alpha-proteins; these beta-chains are only weakly associated with CD3-epsilon and CD3-zeta. Furthermore, KKF responds differently to stimulation through TCR-beta and CD3-epsilon, a functional dissociation that has been ascribed to a CD4+/CD8+ subpopulation of normal thymocytes. KKF's unique TCR structure may offer an explanation for the functional anomalies observed.