Binding of 125I-labelled tumor necrosis factor to Pneumocystis carinii and an insoluble cell wall fraction.

Abstract

We have previously shown that tumor necrosis factor-alpha (TNF-alpha) causes loss of viability of Pneumocystis carinii. In this study, we demonstrate that TNF-alpha irreversibly binds to P. carinii in vitro. The avidity of binding is orders of magnitude greater than that by which it binds to a known sensitive target, L929 cells. A detergent-insoluble fraction of P. carinii, which consists primarily of cyst walls, bound ten times more TNF-alpha per microgram protein as did whole P. carinii.