A commercially available serum-free medium appropriate for studies of macrophage functions in vitro

This report presents results using a commercially available serum-free medium, HL-1, to study growth and differentiation of the macrophage-like cell line Mm-1. Mm-1 cells grown in RPMI 1640 plus 5% calf serum were compared with the same cells acclimated to and maintained in HL-1. The two medium formulations are compared for their ability to support replication of the line as well as their ability to support the expression of non-specific esterase production, lysozyme secretion, Fc receptor expression, and phagocytosis of latex beads. The serum-supplemented RPMI promoted growth of Mm-1 cells slightly better than HL-1, but the HL-1 medium consistently supported differentiated functions of the cells 8-10% above the level expressed in serum-supplemented RPMI at the same cell density. Based on these findings and the low endotoxin levels of HL-1, we conclude that the medium is appropriate for refined physiological studies of macrophage functions in this cell line.