Proliferative, morphologic, and cytochemical characteristics of bovine bone marrow macrophage colonies in liquid culture.

Bovine macrophage colonies were grown in liquid medium. Serum collected from a heifer 3 hours after injection of Pseudomonas aeruginosa endotoxin promoted the growth of macrophage colonies. The optimum concentration of postendotoxin serum was 16%. The numbers of colonies increased exponentially between 3 and 6 days of incubation and leveled off at 6 days. Monoblasts, promonocytes, and macrophages were observed in these colonies. A direct linear relationship between the number of nucleated bone marrow cells cultured and the number of colonies formed was found. The macrophage colony cells were positive for nonspecific esterase activity and were negative for chloroacetate esterase activity. Weak peroxidase activity was noticed in monoblasts, promonocytes, and occasionally in macrophages.