Search for a retroviral cause for sarcoidosis: no evidence from peripheral blood studies

Twenty six patients with sarcoidosis of recent onset or with severe progressive disease were studied for evidence of retroviral infection. Peripheral blood mononuclear cells (PBMC) were cultured in vitro and stimulated with phytohaemagglutinin and interleukin-2. Induction of syncytia (SI) and production of reverse transcriptase (RT) were sought as indicators of possible retroviral infection. PBMC from two patients showed syncytia formation and in one of these two there was associated production of low levels of reverse transcriptase. The remaining patients showed neither RT nor SI activity. The predominantly negative results of this study indicate that sarcoidosis is unlikely to be of retroviral aetiology; however, cell populations from sites of active disease should be studied before drawing this conclusion.