Down-regulation of macrophage lysozyme by lipopolysaccharide and interferon.
Lipopolysaccharide (LPS) treatment of resident mouse peritoneal macrophages (M phi) was found to suppress intracellular as well as secreted lysozyme (LZM). Interferon (IFN) had a similar effect. LZM was identified by the capacity of cell lysates or medium to lyse Micrococcus lysodeikticus, and by the presence of a 14.5 Kd protein band which co-migrated with human LZM in SDS-PAGE and which reacted positively in Western blots with antiserum to human LZM. The size of the 14.5 Kd band decreased sequentially with increasing concentrations of LPS to which the cells were exposed. Although the LPS influence on LZM levels was dose-dependent, the intracellular LZM pool responded more readily than secreted LZM. Maximal intracellular LZM suppression of 80% was obtained with 10 micrograms LPS, whereas secreted LZM was reduced by only 66%. An IFN concentration of 100 U reduced secreted LZM by 24%, whereas 10,000 U of IFN decreased the amount of LZM secreted by 71%. Thioglycolate-elicited M phi had 75% less intracellular LZM than untreated resident M phi. Moreover, thioglycolate-elicited M phi were hyporesponsive to the suppressive effects of LPS added in vitro. Because both LPS and IFN have been shown to stimulate numerous M phi functions, the data are of interest because they support the concept, based on other studies, that agents which are capable of enhancing some M phi activities may concomitantly down-regulate other functions.
D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D007372:Interferons / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000201:enzymology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects; D008264:Macrophages / Q000201:enzymology* / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009113:Muramidase / Q000378:metabolism*
D008070:Lipopolysaccharides; D007372:Interferons; D009113:Muramidase