Pneumocystis carinii factor responsible for reduced phagocytic activity in alveolar macrophages.

Abstract

Alveolar macrophages in hosts that are immunosuppressed and infected with Pneumocystis have a greatly reduced phagocytic activity [5]. Incubation of normal alveolar macrophages with bronchoalveolar lavage (BAL) fluid from P. carinii infected rats also leads to a decrease in phagocytosis [3]. The defect in phagocytosis has been linked to a down-regulation in transcription of the GATA-2 transcription factor [5]. Inhibition ofGATA-2 transcription in normal alveolarmacrophages leads to a reduction in phagocytic ability, and expression of GATA-2 in alveolar macrophages from P. carinii infected rats restores their phagocytic activity [5]. It is not known how P. carinii infection leads to down-regulation of GATA-2 or the decrease in phagocytosis. The current study represents the initial effort to identify factors from P. carinii responsible for the decrease in phagocytosis of alveolar macrophages.