HLA antigens in microscopic polyarteritis (MP) with renal involvement.

Serological HLA-A, B, C, DR and DQ typing was performed in 23 patients with microscopic polyarteritis and renal involvement and in 405 healthy individuals, all of Greek origin. An increased frequency of HLA-A26 (26% vs. 11.3%, x2 = 4.423, p < 0.05) and HLA-A11 (26% vs. 9.6%, x2 = 6.825, P < 0.02), and a decreased frequency of HLA-DR3 (4.3% vs. 24.1%, x2 = 5.935, p < 0.025) were found. Five out of six patients, who did not respond to treatment possessed HLA-DR5. These observations suggest that HLA gene products may influence the clinical expression, as well as the outcome of this disease.