Regulation of macrophage populations. II. Synthesis and expression of Ia antigens by peritoneal exudate macrophages is a transient event.
We have evaluated the biosynthesis and surface expression of I-A antigens by peritoneal macrophages and found that both events terminated during the 1st day in culture, in contrast to the undiminished synthesis and expression of H-2K antigens. This pattern was observed regardless of the means by which the macrophages were elicited, but was subject to modulation for a limited period of time in vitro: phagocytic stimuli were able to augment both I-A synthesis and expression. The loss of I-A and the re-expression after phagocytosis were both reflected in the stimulatory capacity of these macrophages in the mixed leukocyte reaction. Moreover, we found that I-A-bearing macrophages were lost from the exudate in vivo after irradiation. Our data suggest that, as in vitro, this phenomenon is due to the transition of individual macrophages from I-A-positive to I-A-negative, and that constant renewal is required to maintain the I-A-bearing subset in vivo.
D000818:Animals; D003165:Complement System Proteins; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000378:metabolism; D006822:Hybrid Cells / Q000276:immunology; D008087:Listeria / Q000276:immunology; D007959:Lymphocyte Culture Test, Mixed; D008264:Macrophages / Q000145:classification* / Q000276:immunology; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D010461:Peptones / Q000494:pharmacology; D010587:Phagocytosis; D013997:Time Factors
D000949:Histocompatibility Antigens Class II; D010461:Peptones; D003165:Complement System Proteins