HLA antigens in a psoriatic family: comparative studies with MLC, HTC, PLT and serological HLA-DR determinations.

HLA genotypes were characterized in a large family of 48 individuals in three generations. In this family, carriers of the proband's disease-predisposing haplotype commonly expressed clinical signs of illness, manifested as psoriasis and/or arthritic lesions. From these data, and from other family studies, presented previously, we have concluded that cutaneous and/or joint lesions may be signs of disease in carriers of the predisposing HLA haplotype. We have investigated HLA-A, B, C and D/DR antigens in the family members. This gave us the opportunity to evaluate the validity of different assays for the determination of HLA-D alleles in a family material where the MLC tests formed the basis for a correct assignment of HLA-D determinants. The HTC method and the PLT assay were both afflicted with specific typing problems, partly due to the existence of cellular cross-reactions between HLA-D determinants, which seemed to be reminiscent of serological DR crossreactions.