Oligonucleotide typing reveals association of type I psoriasis with the HLA-DRB1*0701/2,-DQA1*0201,-DQB1*0303 extended haplotype

Abstract

Although the pathogenesis of psoriasis is still a matter of debate, there are several lines of evidence supporting the concept of this disease being immunologically mediated with T cells playing a crucial role. Because a considerable portion of the cellular infiltrate in psoriasis consists of activated Thelper cells, expression of HLA class II antigens might be of particular importance for the understanding of its pathogenesis. Therefore, we investigated the HLA type of patients with type I (early onset, positive family history) and type II (late onset, no family history) psoriasis by means of serology (n = 89) and genotyping using sequence-specific oligonucleotide probes (n = 64). Serologic analysis of class I documented the association of type I psoriasis with HLA-Cw6, Q-B13, and -B57, whereas type II psoriasis showed a weaker correlation with HLA-Cw2 and -B27. Genotyping using SSO for class II detected the elevation of the HLA-DRB1*0701/2 allele frequency from 13% in normal population to 36% in type I, but only to 15% in type II psoriatics. Moreover, positive correlations with type I psoriasis were detected for HLA-DQA1*0201 and HLA-DQB1*0303. The HLA-DRB1*0701/2,-DQA1*0201,-DQB1*0303 extended haplotype was found exclusively in type I psoriasis. This is the first report documenting the association of distinct HLA class II alleles with type I psoriasis as detected on the DNA level, an approach both more specific and more sensitive when compared to serology. © 1993.