HLA and complement C4 studies in psoriasis vulgaris.

BACKGROUND. Psoriasis vulgaris is known to be associated with the presence of certain HLA antigens and complement factors but only studies of Western populations have been reported. We investigated the HLA and complement profile in Indian patients with psoriasis vulgaris. METHODS. Sixty-seven patients and 132 normal subjects were typed for class I antigens using 262 sera, and 55 patients and 104 normal subjects were typed for class II antigens using 174 sera. The sera from patients and normals were sent to Japanese laboratories for the study of class III antigens. RESULTS. The study revealed that patients had an increased frequency of A1 (p < 0.0025), B17 (p < 0.0025), Cw6 (p < 0.001) DR7 (p < 0.05) and DQw3 (p < 0.005) when compared to normal controls. Analysis of two and three antigen haplotypes revealed a significant increase in the incidence of all haplotypes involving those antigens which showed a high frequency among patients. A significant association was also found with complement factors C4A6.3 and C4A6,X. However, the relative risk was high for C4BQO (10.73). CONCLUSIONS. Psoriasis in Indians is associated with the A1, B17 and Cw6 but not with B13 antigens and the complement allotypes mentioned above. The strong association with C4 factors may be as a result of a close linkage between the class III region and Ir genes.

Quantitation of HLA antigens on red cells by immunoradiometric assay.

Immunoradiometric assay was employed to quantitate HLA antigens on red cells. Using this technique HLA-B7, HLA-B17 and HLA-A28 were detected on the red cells of all individuals studied irrespective of the serological status of the Bennett-Goodspeed (Bg) antigens. However, HLA antigenic sites for serologically Bg positive red cells were significantly more than that for Bg negative red cells (P less than 0.001). Bga positive red cells possessed maximum number of antigenic sites as compared to Bgb and Bgc positive red cells.