MACROPHAGE POLYKARYON FORMATION INVITRO BY PERITONEAL-CELLS FROM MICE GIVEN INJECTIONS OF SODIUM PERIODATE

Abstract

Peritoneal macrophages from mice that have received 2 separate i.p. injections of the sterile, soluble oxidant NaIO4 form macrophage polykaryons (MP) in vitro; peritoneal macrophages from untreated, peptone-treated or mice infected with BCG do not. The polykaryons are noted after 18-24 h of culture and continue to form over a 60-72-h period. The MP do not form if the macrophage density is < 4 .times. 103/mm. The polykaryons appear in vitro only in cultures with .ltoreq. 1-5 ng/ml [Escherichia coli] lipopolysaccharide (LPS) (amounts of LPS that commonly contaminate culture medium and serum). Hydrocortisone hemisuccinate (2.6 .times. 10-9 M) inhibits MP formation in vitro. Lymphocytes do not influence the polykaryon formation; supernatants from MP cultures do not cause fusion of other macrophages. Microcinephotography demonstrates fusion of the macrophages to form the large polykaryons, which are less motile than uninuclear macrophages. The polykaryons assume different forms; generally, the nuclei (mean, 16.8 nuclei/MP; range, 2-137 nuclei/MP) are centrally located, and the nuclear chromatin of all nuclei appears similar. The MP phagocytize polystyrene spheres and glutaraldehyde-treated [sheep] erythrocytes to the same degree as do uninuclear macrophages when determined as particles/nucleus (phagocytic index), but their phagocytic index of IgG-coated erythrocytes is decreased. Peritoneal macrophages from mice given double injections of NaIO4 are nontumoricidal in the absence of LPS; LPS, in amounts sufficient to inhibit polykaryon formation, renders the macrophages tumoricidal. Populations of macrophages containing MP formed over 3 days of cultures also respond to LPS or macrophage activating factor (MAF) to demonstrate enhanced tumoricidal activity. [MP are seen in various human pathologic states including infections, foreign body reactions, cancer and other conditions such as sarcoidosis and rheumatoid arthritis.].