Major histocompatibility complex class I-specific cytolytic T cells, derived from gld mice, lacking Thy-1, CD4, and...

Thy-1 is a major cell surface molecule expressed on murine thymocytes and peripheral T cells. Its physiological function is unknown, but in vitro studies suggest that Thy-1 may transmit activation signals to T cells and may play a role in the growth and/or differentiation of thymocytes [Kroczek, R. A., Gunter, K. C., Seligmann, B. & Shevach, E. M. (1986) J. Immunol. 136, 4379-4384; Kroczek, R. A., Gunter, K. C., Germain, R. N. & Shevach, E. M. (1986) Nature (London) 322, 181-184]. However, not all mouse thymocytes are Thy-1+ [Scollay, R., Wilson, A., D'Amico, A., Kelly, K., Egerton, M., Pearse, M., Wu, L. & Shortman, K. (1988) Immunol. Rev. 104, 81-120]. In addition, C3H-gld/gld mice accumulate large numbers of Thy-1- (and Thy-1+) T-cell antigen receptor-positive CD8- CD4- (double negative) T cells in peripheral lymphoid organs. Our previous studies of these Thy-1- and Thy-1+ double negatives suggested that lack of Thy-1 expression correlated with diminished capacity to respond to T-cell stimuli. In this report, we describe a Thy-1- alpha/beta T-cell receptor-positive major histocompatibility complex-specific cytotoxic T-cell clone derived from C3H-gld/gld lymph node-residing cells. The data show that, at least in this system, Thy-1 (and CD8/CD4) expression is not required for growth, cytolytic activity, or expression of functional T-cell receptor complexes in vitro and raise the possibility that Thy-1 expression may not be obligatory in vivo for development of cytotoxic T-lymphocyte precursors in gld mice.