Chemiluminescence of macrophages depends upon their differentiation stage: dissociation between phagocytosis and oxygen radical release.

The in vitro differentiation and maturation of resident and activated mouse and human macrophages (M phi) from different anatomical sources was investigated with regard to their oxygen metabolism during zymosan phagocytosis. We found evidence that chemiluminescence (CL) of M phi depends upon their differentiation stage: a) In the absence of any phagocytic stimulus, the human M phi showed a lucigenin-dependent CL background that was approximately 10-fold higher than in mouse M phi and decreased to low levels in resident M phi (monocyte-derived human M phi). This background was reduced by SOD to about 50%. No relevant luminol-dependent background was observed in all mouse and human M phi during culture time. b) Resident and activated mouse and human M phi could be distinguished in terms of their lucigenin-dependent CL during zymosan phagocytosis, which was persistently high in activated M phi, but decreased to comparatively low levels in resident M phi during culture time. This zymosan-elicited CL was almost completely SOD-dependent during all culture time. c) A dissociation between phagocytosis and oxygen radical release is observed: the decrease of both minolul and lucigenin-dependent CL in resident phagocytizing M phi during maturation did not correspond to a decrease of their phagocytic activity. Phagocytosis occurred at a high rate also in the absence of a relevant CL-detectable generation of oxygen radicals. The oxygen radical release, as measured by SOD-inhibitable cytochrome c reduction, paralleled CL during zymosan phagocytosis and declined with maturation of monocytes into M phi. In contrast, the zymosan-induced nitro-blue-tetrazolium reduction increased in mature resident human M phi. Thus, it seems that different metabolic pathways are utilized during phagocytosis in young and mature M phi.