Hamster peritoneal macrophages in vitro: substratum adhesion, spreading, phagocytosis and phagolysosome formation.

A series of manipulations designed to promote cell adhesion and spreading made it possible to maintain satisfactorily hamster peritoneal macrophages in vitro for up to 30 days. The essential requirements for this include in vivo stimulation of the peritoneal cavity, coating of the substratum with polylysine, and the use of HEPES-buffered medium 199 supplemented with horse serum (10%), fetal bovine serum (10%), and lactalbumin hydrolysate (0.5%). Results with the single deletion of the medium components indicate that serum factors are essential for optimal spreading, and horse serum and lactalbumin hydrolysate for the adhesion of in vivo stimulated macrophages on coated glass surface. The thorotrast-labeling method revealed that secondary lysosomes are especially numerous in cultured cells, which otherwise resemble mouse macrophages in cellular organization, as shown by scanning and transmission electron microscopy. More than 95% of the cultured cells manifested cytochalasin B-sensitive phagocytosis of polystyrene latex spheres which, along with morphologic and ultrastructural evidence, indicate the homogeneity of cell population. Erythrophagocytosis of hamster macrophages was demonstrated by scanning electron microscopy and found higher after opsonization implying the presence of receptors for immune ligands on their cell surface.