Detection of gamma interferon in the sera of patients with Behçet's disease.

The serum levels of interferon (IFN) in 58 patients with Behçet's disease were significantly higher than those in 79 normal controls (P less than 0.0001). The average IFN titer was 51.4 +/- 9.3 IU/ml in the patients and 5.9 +/- 1.1 IU/ml in the controls. The patients were then divided into two groups according to the stage of ocular disease. Forty-six patients in the ocular convalescent stage had higher IFN levels (61.3 +/- 11.2 IU/ml) than did 12 patients in the exacerbation stage (13.2 +/- 3.0 IU/ml). Moreover, the kinetics of the IFN level in the circulation of seven patients showed a significant decrease of IFN in the exacerbation stage. IFN activity in sera from patients was destroyed by acid treatment and heating at 56 degrees C for 30 min and was not neutralized with anti-human IFN-alpha and -beta sera. In addition, it was demonstrated that vesicular stomatitis virus inhibitors detected in sera from both the patients and the controls had no effect on our IFN assay. Therefore, antiviral activity detected in sera of patients seems to be due to gamma interferon (IFN-gamma). IFN-gamma may play a significant role in the pathophysiology of Behçet's disease.