Fusion of macrophages following simultaneous attempted phagocytosis of glutaraldehyde‐fixed red cells

Abstract

A model for the fusion of macrophages [human] in areas of chronic inflammation in vivo was presented which is derived from the associations of macrophage fusion in vivo and in vitro. In granulomata, where macrophages are closely packed in the presence of endocytogenic material, this material may on occasion attach simultaneously to more than 1 macrophage. Ensuing endosome margin formation may then lead to the endosome margins of 1 macrophage fusing with those of the other. By causing macrophages to phagocytize glutaraldehyde-fixed red blood cells in vitro under circumstances which more closely reflect in-vivo phagocytosis than the phagocytosis of the red cells by macrophages in a glass adherent monolayer, it was shown that simultaneous attachment leads to macrophage fusion. Giant cell formation in vivo in granulomata apparently results from the process of simultaneous attempted endocytosis.