HL-A TYPING, MIXED LEUKOCYTE REACTIVITY, AND SKIN GRAFT SURVIVAL IN A FAMILY WITH A RECOMBINANT AT THE HL-1 CHROMOSOMAL REGION (MAJOR TRANSPLANTATION REGION)1
SUMMARY The members of family Sch were studied by three different parameters: HL-A typing, mixed leukocyte reaction (MLR), and skin grafting. There were two HL-A-identical, mixed leukocyte reaction-identical siblings (MLR-S); two HL-A-identical, MLR-S-different siblings; and one sibling who was haploidentical to the two sets of HL-A identicals. We have named the HL-A-MLR-S complex the HL-1 haplotype. The father (HL-A1-8/9-12) and two siblings (1-8/2-12) show mutual stimulation in MLR despite identity at the second locus. Similarly, the sibling who is homozygous for HL-A12 showed mutual stimulation in MLR with the parents and all siblings. These results are further proof that the MLR results from a product of a gene linked to the second locus and not the second locus itself. Skin graft rejection times within this family indicate that the gene products responsible for rejection of skin grafts were probably inherited in association with HL-A and independent of MLR-S.