Pneumocystis pneumonia--Los Angeles.

This article describes 5 cases of Pneumocystis carinii pneumonia occurring in homosexual men in Los Angeles California. All 5 patients had previous or current cytomegalovirus and candidal mucosal infection. The men 2 of whom have died ranged from 29-36 years of age. The patients did not know each other and had no known common contacts or knowledge of sexual partners with similar illnesses. The 5 did not have comparable histories of sexually transmitted disease. 4 had serologic evidence of past hepatitis B infection but no evidence of current hepatitis B surface antigen. 2 of the men reported frequent homosexual contact with various partners. All 5 reported use of inhalant drugs. The 3 patients in whom lymphocyte studies were performed had profoundly depressed in vitro proliferative responses to mitogens and antigens. The occurrence of pneumocystosis in these 5 previously healthy men without a clinically apparent underlying immunodeficiency is unusual but seems to reflect some association with a homosexual lifestyle or disease acquired through sexual contact. Cytomegalovirus infection has been shown to induce transient abnormalities of in vitro cellular immune function in healthy homosexual men with and without antibody and a high prevalence of cytomegalovirus infections has been reported among male homosexuals. In additon there is some evidence that seminal fluid may be an important vehicle of cytomegalovirus transmission. Although the role of cytomegalovirus infection in the pathogenesis of pneumocystosis reamins unknown the possibility of P. carinii infection should be carefully considered in previously healthy homosexuals with dyspnea and pneumonia.