Primary and secondary MLR characterization of three allelic variants of HLA-Dw7 segregating in a single family.

Three of four parental haplotypes of a kindred from the Old Order Amish religious isolate carried HLA-DR7 and specificities of the HLA-Dw7 "cluster." Intrafamily primary and secondary mixed lymphocyte responses clearly distinguished the three Dw7-related allelic specificities. Two of the specificities fall within the Dw11 crossreacting group, designated here as Dw11 "short" (Dw11S) and Dw11 "long" (Dw11L), while the third is more closely related to Dw7. Reaction patterns in this family illustrate the complexity of antigen recognition in primary and secondary mixed lymphocyte responses and the important role played by the responder cell in generating discriminatory primed lymphocyte typing reagents.