Generation of discriminatory PL against HLA-D antigens not detected by serology.

A family was studied in which the father and the mother were both homozygous for the HLA-DR antigens. All children responded to the parents in MLC, even though each had a copy of the parental DR antigen, implying that they recognized a difference. When the father or the mother was sensitized in PLT against any child, all siblings could restimulate equally well. However, by sensitizing a family member with one copy of the DR phenotype against another family member with the alternate form of the phenotype, discriminatory PL could be produced. This may help define the subtypic specificities of PL antigens.