Association of HLA antigens with the clinical course of sarcoidosis and familial disease

Patients with sarcoidosis usually have a benign course and a favourable prognosis. Although spontaneous remission is common, a progressive disease with a severe prognosis occurs in a small but significant number of patients. The aim of this study was to evaluate the potential significance of HLA antigens as a clinical marker on the outcome of sarcoidosis patients. We conducted a retrospective cohort study for HLA class I and II allels in 74 sarcoidosis patients and 72 healthy transplant donors. Bronchoscopy and bronchial biopsies were performed in each patient. Two or more positive bronchial biopsy samples revealing granulomatous inflammation was defined as diffuse while one positive biopsy sample was considered as limited endobronchial disease. Three or more extrapulmonary organ involvement was denoted as severe extrapulmonary disease. The patients were followed-up at least for eight years.  Incidence of progressive disease was significantly high in patients with positive HLA-DRB1*07, DRB1*14 (p<0.05) and DRB1*15 (p <0.001) allels. HLA-DRB1*14 and DRB1*15 were associated with severe extrapulmonary organ involvement (p<0.001). HLA-DRB1 *14 (p<0.05) and DRB1*15 (p<0.001) were significantly more frequent in patients with diffuse endobronchial involvement. Incidence of familial disease was 14.8% with a 6.7% identical HLA typing. Presence of HLA class I and II allels may influence the severity and prognosis of sarcoidosis significantly. Apart from defining genetic susceptibility, HLA class I and class II allels appear to be relevant and crucial markers for the to predict the clinical outcome of sarcoidosis. Distinct heterogenity of sarcoidosis may arise from the particular presence of different allels in invidual patients.