INTERLEUKIN-8 AND THE NEUTROPHIL RESPONSE TO MUCOSAL GRAM-NEGATIVE INFECTION

Urinary tract infections activate a mucosal inflammatory response, whi ch includes cytokine secretion and neutrophil influx. The mechanisms i nvolved in the neutrophil influx have not been identified. Interleukin -8, a potent chemoattractant for neutrophils, is produced by urinary t ract epithelial cell lines in vitro. This study analyzed the human IL- 8 response to deliberate Escherichia coli infection of the urinary tra ct. Urine and serum samples were obtained before and after intravesica l instillation of E. coli. Neutrophil numbers were determined on uncen trifuged urine, and IL-8 levels were measured by ELISA. A urinary IL-8 response was found in all patients after bacterial instillation, but no serum IL-8 was detected. There was a strong correlation between uri nary IL-8 levels and urinary neutrophil numbers. The same E. coli stra ins used to colonize the patients stimulated IL-8 production in urinar y tract epithelial cells. The level of IL-8 secreted by epithelial cel l lines was influenced by the fimbrial properties of the E. coli. Thes e results demonstrated that E. coli elicit a mucosal IL-8 response in humans, and suggested that IL-8 is involved in the onset of pyuria. Ep ithelial cells may be an important source of IL-8 during urinary tract infection.