Interleukin-8: an important neutrophil chemotaxin in some cases of exudative pleural effusions.

It was hypothesized that IL-8, a neutrophil chemotaxin, contributes to the influx of neutrophils into the pleural cavity of patients with pleural effusions. Pleural fluids were collected from 57 patients including 13 with effusions due to congestive heart failure, 28 with pleural involvement by carcinoma, 5 with empyema, 4 with parapneumonic effusions complicating bacterial pneumonia, 3 with hemothorax, 3 with tuberculosis, and 1 with rheumatoid arthritis. All exudate groups had significantly higher IL-8 concentrations than the CHF group (p < .001). In 18 of the exudate fluids, the concentrations of IL-8 was equal to or in excess of the optimal concentration of IL-8 which causes neutrophil chemotaxis in vitro. Between 20 and 90% of the chemotactic activity in the fluids was removed by absorbing the IL-8 with an IL-8 affinity column. These data showed that IL-8 is a major chemotaxin in the fluid. The percentage of neutrophils in the fluids was not correlated with the IL-8 concentration. Although TNF alpha, a potent stimulator of IL-8 production, is present in some pleural effusions, no correlation was found between the concentrations of IL-8 and TNF alpha in the fluids. The data suggest that IL-8 contributes to the neutrophil influx into the pleural space of patients with pleural exudates in conjunction with other chemoattractants. It is unlikely that TNF alpha is the sole stimulus for the IL-8 production in pleural disease states.