Autoreactive HLA-DR-specific autoreactive T-cell clones: possible regulatory function for B lymphocytes and hematopoietic precursors.

The physiological significance of autoreactive T cells derived from normal individuals and activated in the absence of any identifiable foreign antigen by class II MHC-syngeneic molecules remains unexplained. Here we report that autoreactive T-cell clones (Tilkin et al. 1987) proliferate and are able to kill autologous or syngeneic EBV-cell lines but not autologous or syngeneic HLA-Class II-positive PHA-activated T-cell blasts. Furthermore, they are able to efficiently inhibit in vitro the differentiation of CFU-GM and BFU-E colonies, in agreement with the well-known observation that hematopoietic precursors express HLA-DR molecules (Cannistra et al. 1986). The reasons why the autoreactive clones do not recognize T-cell blasts, as well as their possible implications in regulatory mechanisms involving HLA-class II molecules are discussed.