Pneumocystis carinii pneumonia due to corticosteroids.

A patient receiving long-term corticosteroid therapy for asthma had two episodes of Pneumocystis carinii pneumonia (PCP) 8 years apart. She had no other causes of immunosuppression. Experimental evidence indicates that corticosteroid administration causes a reduction in T lymphocytes mediated by suppression of cytokines. Corticosteroid therapy is a rare but possible independent predisposition to PCP.