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January 1991

Tumor Necrosis Factor and Endotoxin Can Cause Neutrophil Activation Through Separate Pathways

Arch Surg. 1991;126(1):70-73. doi:10.1001/archsurg.1991.01410250076012

• We investigated the possibility that tumor necrosis factor (TNF) mediates neutrophil activation by endotoxin. The number of C3b receptors on the neutrophil cell-surface was used as the indicator of activation, as assessed by indirect immunofluorescence. Incubation of buffy-coat neutrophils with TNF-α for 30 minutes at 37°C caused neutrophil activation, increasing C3b receptor–dependent fluorescence from 340 with buffer alone to 580 with TNF (250 pg/mL). Increasing amounts of anti-TNF IgG progressively inhibited neutrophil activation by TNF (250 pg/mL). Addition of the active dose range of anti-TNF to neutrophils incubating in endotoxin (10 ng/mL) did not affect the degree of endotoxin-mediated neutrophil activation. Mixtures of neutrophils with the 50% suppressive dose of anti-TNF and varying endotoxin concentrations showed the same degree of neutrophil activation as mixtures without the antibody. Thus, an antibody that can inhibit TNF-mediated neutrophil activation does not inhibit endotoxin-mediated neutrophil activation. We conclude that endotoxin and TNF can activate neutrophils through separate pathways.

(Arch Surg. 1991;126:70-73)