A case of Pneumocystis carinii in pleural fluid with cytologic, histologic and ultrastructural documentation

Pneumocystis carinii involvement of the pleural cavity in a patient with the acquired immune deficiency syndrome was documented by cytologic as well as scanning and transmission electron microscopic study of pleural fluids. Histologic examination of the pleura and the subpleural lung revealed vasculitis and infarctlike necrosis as well as P carinii in the tissue. Although a few cases of extrapulmonary P carinii infection have been reported, this appears to be the first time its presence in pleural fluid has been documented.     

Glucan synthesis in Pneumocystis carinii.

Rat-derived Pneumocystis carinii lysed with sodium deoxycholate catalysed the incorporation of uridine diphosphoglucose into an insoluble polymer. This enzyme activity was present in both the pellet and the supernatant when the P. carinii preparations were centrifuged. The polymer whose production was catalysed by the supernatant was examined by mass spectrometry and found to be an alpha 1----4 glucan, which is either unbranched or has relatively few branches. Polymer formation was completely inhibited by the addition of alpha amyloglucohydrolase to the supernatant. Polymer formation in the pellet of deoxycholate P. carinii preparations, unlike that in the supernatant, was partially resistant to alpha amyloglucohydrolase. The soluble glucan synthase activity in the supernatant was stable for more than 30 h at room temperature and was approximately 50 times more active on a cell-to-cell basis than the supernatant from deoxycholate preparations of the yeast Saccharomyces cerevisae.     

Pneumocystis carinii polyamine catabolism.

DL-alpha-Difluoromethylornithine (DFMO) causes polyamines of the AIDS-associated opportunistic pathogen Pneumocystis carinii to diminish 15 times more rapidly than mammalian host cells. The proposed mechanism was that, unlike mammalian cells, P. carinii is unable to regulate polyamine catabolism when synthesis is blocked. To test this, the responses of the polyamine catabolic enzymes spermidine/spermine acetyltransferase (SSAT) and polyamine oxidase (PAO) were determined using a new high-performance liquid chromatography assay to measure the products of these enzymes. The specific activities in untreated Pneumocystis carinii were 1.78 +/- 0.5 pmol min(-1) mg protein(-1) for SSAT, similar to mammalian cells, and 6.42 +/- 0.8 pmol min(-1) mg protein(-1) for PAO, 19% of that of mammalian cells. DFMO treatment for 12 h caused reductions of only 11 and 4% in SSAT and PAO, respectively, despite polyamine reductions of 94, 96, and 90% for putrescine, spermidine, and spermine, respectively. The P. carinii SSAT K(m) value of 25 microM spermidine is 20% of that of mammalian cells, and the PAO K(m) value of 14 nM N(1)-acetylspermidine is 0.01% of that of mammalian cells. Acetylated polyamines continue to be lost from P. carinii even when exposed to DFMO. Collectively, these results support the hypothesis that P. carinii is unable to regulate polyamine catabolism.     

Bronchoalveolar lavage fluid cytology in patients with Pneumocystis carinii pneumonia

OBJECTIVE: To evaluate bronchoalveolar lavage (BAL) cytology and organism burden in patients with Pneumocystis carinii pneumonia (PCP) who were infected with the human immunodeficiency virus (HIV) and in those with other immunodeficiencies. STUDY DESIGN: BAL fluid samples from patients with PCP were selected (HIV-infected patients, n = 15; patients with other immunodeficiencies, n = 11). May-Grünwald-Giemsa-stained cytocentrifuge preparations were evaluated. Foamy alveolar casts (FACs) and P carinii clusters were counted. RESULTS: The numbers of FACs and P carinii clusters in BAL fluid samples of HIV-infected patients were significantly higher as compared to those in samples from patients with other immunodeficiencies. Striking cytologic findings observed in half the samples from both patient groups included the presence of foamy alveolar macrophages, activated lymphocytes, plasma cells and reactive type II pneumocytes. Furthermore, a peculiar cell type, "nonidentified cell" (NIC), was observed almost exclusively in BAL fluid samples from HIV-infected patients. CONCLUSION: BAL fluid samples from HIV-infected patients with PCP displayed higher organism burdens as compared to those from patients with other immunodeficiencies. Moreover, cytologic findings suggestive of noninfectious lung conditions were common in BAL fluid samples obtained from patients with PCP. Further study is required to elucidate the identity of the NIC cell type.     

Pneumocystis carinii pneumonia in the rat model.

Groups of barrier-raised but not certified virus-free Sprague-Dawley rats, obtained from the same source over the course of several years, were placed on an identical immunosuppressive regimen. This caused reactivation of latent Pneumocystis carinii infection, manifest as P. carinii pneumonia (PCP) of varying severity. Rats were euthanized after 9-12 wk of immunosuppression. An assessment of the severity of the induced PCP was made, based on the total number of organisms extracted from the lungs and their ability to proliferate in short-term cell culture. Serum samples obtained at sacrifice were tested by indirect immunofluorescence for antibodies to coronavirus, parvovirus, Sendai virus, pneumonia virus of mice (PVM) and Mycoplasma pulmonis. A total of 60 rats were examined. Thirty-four of these (57%) developed moderate or severe PCP. No antibodies were detected to either coronavirus or Mycoplasma pulmonis in any of the rats. Although antibodies were detected to parvovirus in 13/60 (22%), to PVM in 29/60 (48%), and to Sendai virus in 47/60 (78%), there was no apparent correlation between the presence or absence of antibodies to these agents and the severity of PCP. Sequential observations during the course of immunosuppression are needed to clarify the role of concomitant infections in the development of PCP.     

Expression cloning of Pneumocystis carinii antigens.

We undertook expression cloning of Pneumocystis carinii antigens to overcome the difficulties encountered in purification of these antigens. Using monoclonal antibodies to the P. carinii gp120 antigen and polyclonal rabbit antiserum to rat-derived P. carinii, we have isolated cDNA clones encoding immunoreactive moieties. A cDNA clone encoding the 3' portion of a 45-55 kDa antigen of rat-derived P. carinii, was the most abundant clone isolated. The peptide encoded by this cDNA has a novel sequence with a repeated motif rich in glutamic acid residues. Affinity-purified antibodies to this peptide reacted with the 45-55 kDa band of rat-derived P. carinii. The fusion protein was recognized by serum antibodies from rats with natural exposure to P. carinii. The production of this recombinant protein should allow more detailed studies of the host-parasite relationship of this important opportunistic infection.