Reconstitution of immune responses to Pneumocystis carinii pneumonia in patients with HIV infection who receive highly active antiretroviral therapy.

We describe a reconstitution syndrome of immune responses to Pneumocystis carinii pneumonia (PCP) in 2 HIV-infected individuals who received highly active antiretroviral therapy (HAART). Patient 1, who had been successfully treated for PCP 3 years before the initiation of HAART, developed cough and pulmonary shadows 6 weeks after the start of HAART. Patient 2 was introduced HAART immediately after completing the responsive treatment of PCP, and then showed dyspnea and diffuse pulmonary infiltrates 7 months later. Histologic findings of lung-tissue samples showed granulomatous tissue (patient 1) and organizing pneumonia with thickening of alveolar septa (patient 2), and immunohistochemical findings revealed both CD4 and CD8 cell subsets represented in the lesions. The tissue and bronchoalveolar lavage (BAL) specimens showed no organisms, but PCR methods with the BAL samples were positive for P. carinii DNA. It is hypothesized that these second respiratory episodes may have arisen as immune reconstitution syndrome in response to residual P. carinii antigen in the lung.