The effect of corticosteroid treatment on the cell surface glycocalyx of the rat pulmonary alveolus: relevance to the host-parasite relationship in pneumocystis carinii infection.

Pneumocystis carinii infection is characterized by the attachment of P. Carinii to host alveolar type I cell and propagation of the organism with corticosteroid administration. We have examined the effects of corticosteroids on the cell surface glycocalyx of the pulmonary alveolus in rats by ultrastructural histochemistry using cationized ferritin, ruthenium red and concanavalin A-horseradish peroxidase techniques. In rats treated for 4 and 6 weeks, the amount of the alveolar cell surface glycocalyx was markedly decreased by all three techniques. The changes were most pronounced at the cell surface of the type I pneumocyte, and this may be important in the pathogenesis of P. carinii pneumonia.