HLA antigen distribution in different clinical subgroups demonstrates genetic heterogeneity in lichen planus.

HLA-A, B, Cw, DR and DQ antigens were serologically determined in 105 patients suffering from lichen planus (LP). Of these patients, 87 bad idiopatbic LP and 18 bad secondary LP. In the first group, 43 bad cutaneous LP without mucosal lesions, 17 bad cutaneous LP with mucosal lesions and 27 bad purely mucosal LP. No HLA antigen was found to be significantly associated with secondary LP or with mucosal idiopathic LP. In cutaneous idiopathic LP with or without mucosal lesions, the HLA-DR1 and DQI antigen frequency was significantly increased, and that of HLA-DQ3 significantly decreased. Among the HLA-DR1 cutaneous idiopathic LP patients, 78.5% carried the DRB1*0101 allele, and 21.4% the DRB1*0102 allele, compared with 35-7 and 67-8%, respectively, of the HLA-DR1 controls. Our data demonstrate that idiopathic LP is influenced by HLA-associated genetic susceptibility and resistance factors not involved in secondary LP, and that cutaneous idiopathic LP is a genetically and therefore pathogenetically different condition from purely mucosal idiopatbic LP. [ABSTRACT FROM AUTHOR]