The etiology of these abnormalities was also unclear. Since HIV infection resulted in profound suppression of T-cell macrophage-mediated immunity in AIDS and since there were significant abnormalities in B-cell lymphocyte function resulting in abnormalities of humoral immunity, there were frequently life threatening superinfections by bacterial, fungal, parasitic, and viral organisms. Some of these, such as herpes simplex, cytomegalovirus, cryptococcosis, toxoplasmosis and histoplasmosis, were known to cause pericarditis and myocarditis in the absence of AIDS so the presence of definite myocardial disease in AIDS did not prove that the disease was due to the HIV organism.