Effect of urine and urine components on the chemiluminescent response of bacteria-stimulated polymorphonuclear leukocytes.

The role of polymorphonuclear leukocytes (PMN) found in urine during infectious episodes is still unknown. Opsonophagocytosis of Escherichia coli by normal blood PMN in the presence of urine was measured using a chemiluminescence (CL) assay. PMN were challenged by a type I fimbriated E. coli strain shown to elicit a CL response through attachment to the mannose-containing receptors on the leukocytes. In the presence of urine the CL response decreased significantly. Urine osmolality due to inorganic salts partially caused this decrease. A higher inhibitory effect was elicited by urea. Under otherwise similar conditions, the presence of an additional CL-inhibiting factor, most probably a protein, was detected in urine; however, its identity has not yet been defined. In vitro and in vivo urine dilution improved PMN function. No difference in effect on CL response was found between urine obtained from 25 children with recurrent urinary tract infections and urine from 15 age-matched controls.