Differentiation of fibroblast-like cells into macrophages.

Differentiated cells with the morphological, enzymatic, antigenic, and functional characteristics of macrophages formed when a variety of nontransformed and transformed fibroblast-like mouse embryo cell lines were grown in a medium supplemented only with human plasma. Differentiated cells contained numerous lysosomes and phagosomes, nonspecific esterase and acid phosphatase activities, and cell surface la antigens and were capable of phagocytosis of iron particles. Differentiated cells were also growth arrested in the G1 phase of the cell cycle, but both growth arrest and differentiation were reversible processes. These observations suggest that cells with the morphology of fibroblasts have the capacity to undergo nonterminal differentiation into macrophages.