Elevated levels of CD4 antigen in sera of human immunodeficiency virus-infected populations.

CD4 antigen levels in sera from asymptomatic intravenous drug users and homosexuals and patients with lymphadenopathy, acquired immunodeficiency syndrome-related complex, or acquired immunodeficiency syndrome were quantitated. Like soluble CD8, CD4 antigen levels were elevated in human immunodeficiency virus-seronegative asymptomatic intravenous drug users and homosexuals, probably reflecting infections such as cytomegalovirus, Epstein-Barr virus, and hepatitis B virus infections. The sera from human immunodeficiency virus-seropositive groups of patients with human immunodeficiency virus infection also had elevated levels of CD4 antigen, presumably reflecting infections like cytomegalovirus and human immunodeficiency virus infections.