The local role of tumor necrosis factor alpha in the modulation of neutrophil function at sites of inflammation.

OBJECTIVE

To examine the hypothesis that tumor necrosis factor alpha (TNF-alpha) is an important local modulator of neutrophil function in the inflammatory microenvironment.

DESIGN

In vitro studies of host defense.

PATIENTS

A volunteer sample of healthy subjects.

INTERVENTION

Exudative neutrophils were collected from skin-blister chambers and functionally compared with blood neutrophils.

METHODS

Tumor necrosis factor alpha levels at sites of inflammation and neutrophil exudation were determined and compared with serum concentrations. Flow cytometry was used to evaluate neutrophil microbicidal activity and N-formyl-methionyl-leucyl-phenylalanine-induced changes in intracellular calcium and superoxide production. In vitro TNF-alpha was used to evaluate the nature and dose response of TNF-alpha-induced changes in neutrophil function.

RESULTS

Exudative neutrophils have an increased responsiveness to subsequent N-formyl-methionyl-leucyl-phenylalanine stimulation, as determined by changes in intracellular calcium. Microbicidal activity and superoxide production are also up-regulated compared with circulating neutrophils. The exudative microenvironment contains TNF-alpha at local levels that are capable of significantly enhancing neutrophil host defense.

CONCLUSIONS

Tumor necrosis factor alpha may serve to enhance neutrophil function at sites of inflammation. Neutrophils become more cytotoxic and have an enhanced ability to respond to weak environmental signals.