HLA-D related (DR) antigens in various kinds of myositis

Forty-eight patients with various kinds of myositis were studied for HLA-A,B.C. and DR antigens and compared to both local and 7th International Workshop controls. No A.B. or C antigens were increased except for B8 in white patients ($\text{6}\text{9\%}\text{or}\text{67\%)}\text{p}\text{= 0.005,}\text{pc}\text{=}\text{NS}$)_ and for B7 in black patients ($\text{6}\text{9}\text{or}\text{67\%) (}\text{p}\text{= 0.02,}\text{pc}\text{=}\text{NS}$). HLA-DR3 occurred in $\text{8}\text{12}$. or 67%, of whites with polymyositis (PM) as compared to 23% of white controls (p=0.003, pc=0.02). HLA-DRω6 was found in $\text{7}\text{9}$, or 78%, of blacks with PM compared to 26% of black local controls (p=0.005, pc=0.04) and 38% of black Workshop controls (p=0.005, pc=NS). Dermatomyosis (DM) patients, however, showed no increased frequencies of any HLA antigens. HLA-DR4 was decreased overall (p=0.005, pc=0.04). The immunogenetic differences between PM and DM suggest that they are pathogenetically different disorders.