The HL-A7 histocompatibility antigen in sarcoidosis in relation to tuberculin sensitivity.

Eighty cases of sarcoidosis have been investigated. In all except eight patients a histological verification of the diagnosis was obtained by mediastinoscopy or liver biopsy. The HL-A7 antigen was not increased in the entire group. However, in the group of patients with a negative sensitivity to tuberculin after the appearance of the disease there was a significant increase compared with controls. In the patients with a positive reaction, there was a complete absence of HL-A7. The HL-A system therefore does not seem to influence the liability to contract sarcoidosis, but once this condition has developed HL-A7 positives are more likely to lose cellular immunity to tuberculin and to reveal symptoms.