HLA-DQ-specific autoreactive T cell clone with helper and cytotoxic functions

To clarify the existence and the possible function of DQ-specific autoreactive T cells, we established a novel autoreactive T cell clone (28B8) responding to self-DQ molecules from an unimmunized normal subject. Blocking studies with monoclonal antibodies (mAbs) to HLA class II antigens and alloreactive response of the clone revealed that the clone recognized DQ molecules defined by a DR1-DQw5 haplotype. Clone 28B8 markedly induced autologous B cells to produce immunoglobulins, and was also cytotoxic against autologous lymphocytes, as well as against allogeneic lymphocytes with a DR1-DQw5 haplotype. These findings indicate that DQ antigens are involved in autoreactivity and stimulate autologous T cells that may have potent immunoregulatory functions.