Human Ia-like DRw lymphocyte antigens stimulating activity in primary mixed lymphocyte reaction.

The intensity of the primary mixed lymphocyte reaction (MLR) seems to be influenced by at least two distinct determinants of the HLA-D region: the HLA-Dw stimulating products and the human Ia-like B lymphocyte DR (D-related) antigens. In three families, the primary MLR is significantly higher in case of HLA haploidentity, when stimulating and responding cells differ with regard to both Dw and DRw determinants, than when only Dw products are different. Thus, an additional effect of DR antigens during primary MLR is observed. The role of DRw antigens in primary MLR and the results obtained by a primed lymphocyte test which can discriminate between Dw3 and DRw3, indicate that DRw and Dw products could be distinct determinants.