Production of tumor necrosis factor α by resident and activated murine macrophages

Alveolar macrophages (AmΦs), resident peritoneal macrophages (RPmΦs), and thioglycolate-elicited peritoneal macrophages (TGPmΦs) were isolated from C57BL/6 mice and incubated with lipopolysaccharide (LPS), stimulated cell supernatant, or recombinant interferon γ (IFN-γ) for 24 h. Tumor necrosis factor (TNF) in cell-free supernatants was measured by enzyme-linked immunosorbent assay. AmoΦs incubated with 10³ ng/ml LPS produced 50 times more TNF than RPmΦs and 5 times more than TGPmΦs, and LPS alone induced maximum TNF production by AmΦs. Stimulated cell supernatant or recombinant IFN-γ alone did not induce TNF production. A combination of LPS with stimulated cell supernatant or IFN-γ had only a limited synergistic effect on TNF production by AmΦs. However, both LPS and stimulated cell supernatant or recombinant IFN-γ induced maximum TNF production by RPmΦs and TGPmΦs. TGPmΦs showed greater sensitivity to LPS and stimulated cell supernatant or IFN-γ with regard to TNF production than the other macrophage populations investigated.