The products of the
HLA-D region and their correlation to
psoriasis vulgaris was studied using the primed lymphocyte typing (PLT) assay. In families with one healthy and one psoriatic parent and one psoriatic child primary MLC (mixed lymphocyte culture) stimulation was carried out between responder cells from the healthy parent and stimulator cells from the psoriatic child. In this way 21 PLT
reagents directed against putative
psoriasis-associated
lymphocyte activating determinants were produced. Three
reagents that gave clear bimodal stimulation patterns against lymphocytes of 51
psoriasis patients were further tested against 78 controls. Specificity of these
reagents was studied using homozygous typing cells (HTC's) as stimulators. Compiled data show that cells from DR7 positive psoriatic patients give higher restimulation of these PLT
reagents than do cells from healthy DR7 positive controls. In addition, a higher frequency of
psoriasis patients compared to controls gave significant restimulation. Therefore we concluded that these PLT
reagents recognized at least partly different DR7 associated determinants in the
psoriasis patients and in controls. The reason is either that
psoriasis patients carry a different lymphocyte activating DR associated specificity or, alternatively, that restimulation was caused by products of a distinct
psoriasis associated locus in linkage disequilibrium with D/DR7 or of a determinant recognized together with D/DR7 as a restriction
element. These data further support the notion that
psoriasis is a disease with primary HLA associations to both class I and class II MHC genes.