Evidence of Pneumocystis carinii in cell line cultures infected with peripheral blood mononuclear cells isolated from AIDS patients with P. carinii pneumonia.

The detection of Pneumocystis carinii was investigated in an in-vitro system consisting of a human lung epithelial cell line (A-549) inoculated with infected peripheral blood mononuclear cells (PMBC) from HIV-infected patients with proven or suspected P. carinii pneumonia (PCP), and from HIV-negative patients with other lung infections. Supernates from cultures were sampled daily and evaluated for the presence of P. carinii by Giemsa and immunofluorescence staining. P. carinii was isolated from 98 (95.1%) of 103 culture supernate samples from patients with proven pneumocystosis and 45 (66.1%) of 68 from patients with suspected PCP 40 or 72 h after PBMC inoculation. This system has been shown to support the growth of P. carinii but did not seem to be adequate for the production of large numbers of organisms, although long-term survival in vitro for up to 3 weeks was observed. Recovery of P. carinii from infected PBMC strongly supports previous observations about its ability to disseminate haematogenously and could represent a further advance in understanding the pathogenesis and diagnosis of PCP.