Specific inhibition of T-cell-mediated cytolosis by alloantiserum against HLA-D-related (DR) antigens.

Lymphocytes sensitized against HLA-A and B region-compatible, HLA-D region-incompatible stimulators were cytotoxic for target cells having the correct HLA-D antigens. This form of cytotoxicity was inhibited by platelet-absorbed pregnancy sera containing antibodies to the HLA-DR antigens of the target cells but not by sera with antibodies against other DR antigens. This form of CML was also inhibited by unlabeled monocytes and B cells of the relevant HLA-D specificity but not by T lymphocytes from the same donors.