Complexity of the HLA-D region studied by primed-lymphocyte test

The results obtained by mixed lymphocyte culture (MLC), HLA-D and -DR typing, and primed lymphocyte test (PLT) in the F. family give some indication of the complexity of the HLA-D region in man. Two siblings identical for HLA-A, -B, -C, -D, and -DR by typing are mutually MLC-stimulatory. PLT studies indicate that one of these siblings expresses D-region determinants of both of the mother's haplo-types, suggesting an intra-D recombinant. These results suggest that the D region contains genes for a number of different determinants.