The use of mouse serum and the presence of non-adherent cells for the culture of mouse macrophages.

Mouse serum (MS) was investigated as an alternative to fetal calf serum (FCS) as a medium supplement for the culture of murine macrophages. Peritoneal macrophages were successfully cultured in medium supplemented with 1-20% MS and were able to produce superoxide anions in response to stimulation with phorbol myristate acetate (PMA) and to phagocytose antibody-coated erythrocytes effectively. Macrophages cultured in the presence of 5% or 20% FCS showed a generally augmented response to PMA, raising the possibility that they had been 'primed' by constituents or contaminants of FCS. Lipopolysaccharide-elicited macrophages initially showed vigorous in vitro responses to PMA which decreased with increasing culture time in MS-supplemented medium. This 'de-differentiation' of elicited macrophages could be due to the absence of LPS contamination and foreign protein when autologous serum is used as a medium supplement. In all cultures the presence of non-adherent cells for the first 24 h increased the number and superoxide response of adherent cells. MS is a convenient, reliable and inexpensive alternative to FCS as a medium supplement for murine macrophage cultures.