The frequency of
HLA-A, B, and Cw
antigens as well as the
antigens expressed preferentially on B cells and monocytes (DRw and Ia-like) was examined in a normal population and two related disease populations,
psoriasis and
psoriatic arthritis.
HLA antigens distinguishing the two disease populations were found. Psoriatic patients demonstrated an increase in frequency of
HLA-A1, B17, and B13. Patients with
psoriatic arthritis demonstrated an increased frequency of
HLA-A26, B38, and DRw4.
Antigens showing a common increase in frequency in the two disease populations were
HLA-Cw6, DRw7, and Ia744. These results demonstrate genetic differences as well as similarities in the two populations of patients with the common clinical feature of
psoriasis. In addition to the above analysis, we examined the association of individual
alloantigens elevated in frequency in the diseased population. These same
alloantigens were examined for association in the normal population. This analysis revealed HLA
antigen associations in the two disease groups that differed from the association of several
antigens in the normal population. The results suggest that at least two genetic factors, one mapping in the
HLA-A, C-B region and one mapping in the
HLA-B-DRw region are associated with the disease states. Thus, multiple factors controlled by genes in the major histocompatibility complex appear to contribute to the disease entities under investigation.