Human autoreactive (Th0) CD4(+) T-cell clones with cytolytic activity recognizing autologous activated T cells as the...

In attempt to obtain a clue to understanding possible physiological roles played by autoreactive T cells, autoreactive T-cell clones originally derived from an allogeneic mixed lymphocyte culture have been analyzed for their target spectrum, lytic function and cytokine profiles. Five CD4(+) T-cell clones established from allogeneic MLR, in which the stimulator cells shared certain class II MHC antigens with the responder, turned out to be reactive to autologous PBL. Among these, three clones were cytolytic against autologous B-cell line. These three cytolytic autoreactive clones were shown to be capable of specifically lysing autologous activated T cells expressing class II MHC molecules, raising possibility that such autoreactive clones might play a role in negatively regulating T cell responses. Cytolysis by an autoreactive clone 21C5 was inhibited completely by concanamycin A (CMA) known as a specific inhibitor of perforin, suggesting an involvement of the perforin/granzyme system. T-cell clones derived from the same MLC showed distinct correlation between their specificity and lymphokine profiles. Thus, the three cytolytic autoreactive clones belonged to Th0, whereas the two noncytolytic autoreactive clones belonged to Th2 and three alloreactive CD4(+) clones derived from the same culture were of Th1 type.