A mitogenic factor for macrophages present in rat serum (Abstract)
Rat macrophages, obtained from a mixed white cell population collected by peritoneal lavage, were plated out at 6 × 105 cells cm2 in Medium 199 containing 20% fetal calf serum, 25 mol/l HEPES pH 7.4 and antibiotics and were aged for 3 days in culture. The cells were then cultured for a further 6 days in fresh medium containing 20% fetal calf serum, tritiated thymidine and 0–50% normal rat serum. Mitogenesis was assessed by counting the percentage labelled nuclei following autoradiography. Colony stimulating activity was assessed using thioglycolate elicited rat peritoneal macrophages harvested 3 days after injection. The cells were seeded at 600 cells/cm2 in medium as above, in the presence or absence of rat serum or rat serum fractions and colonies were counted after 28 days incubation.