HLA-ANTIGEN DISTRIBUTION IN DIFFERENT CLINICAL SUBGROUPS DEMONSTRATESGENETIC-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 had idiopathic LP and 18 had secondary LP. In the first group, 43 had cuta neous LP without mucosal lesions, 17 had cutaneous LP with mucosal les ions and 27 had purely mucosal LP. No HLA antigen was found to be sign ificantly associated with secondary LP or with mucosal idiopathic LP. In cutaneous idiopathic LP with or without mucosal lesions, the HLA-DR 1 and DQ1 antigen frequency was significantly increased, and that of H LA-DQ3 significantly decreased. Among the HLA-DR1 cutaneous idiopathic LP patients, 78.5% carried the DRB10101 allele, and 21.4% the DRB1*0 102 allele, compared with 35.7 and 67.8%, respectively, of the HLA-DR1 controls. Our data demonstrate that idiopathic LP is influenced by HL A-associated genetic susceptibility and resistance factors not involve d in secondary LP, and that cutaneous idiopathic LP is a genetically a nd therefore pathogenetically different condition from purely mucosal idiopathic L.P.