Preservation of Fc gamma receptor-mediated particle phagocytosis and binding with rat alveolar macrophages adhered to a plastic substrate in a serum free system.

Functional differences between adherent macrophages and macrophages in suspension have been repeatedly reported. During the course of developing serum-free phagocytic assays to evaluate Fc gamma receptor (Fc gamma R)-mediated phagocytosis by rat alveolar macrophages (AM) we found Fc gamma R-mediated phagocytosis by Rat AM in suspension was markedly greater than when these cells were bound to plastic substrate in protein-free medium. This dissimilarity in performance was related, in part, to a plastic substrate-associated loss in Fc gamma R-mediated phagocytosis in that this cell function was preserved when monolayers of AM were formed in culture medium containing a low concentration of bovine serum albumin (BSA). The results of particle binding studies suggest the diminished phagocytic activities of AM in monolayers formed in the absence of BSA was due to a loss in the functional expression of Fc gamma R.