[Superoxide anion generation of human polymorphonuclear leukocytes in urine].

In order to clarify the role of polymorphonuclear leukocytes (PMNs) in the defence mechanism of the urinary tract, we investigated the superoxide anion (O2-) generation of PMNs in the urine. We tested urines mixing concentrated urine with diluted ones in various ratios. Peripheral blood derived PMNs were stimulated in tested urines or phosphate buffer solution (1M, pH 7.0) with phorbol-myristate acetate and O2- generation of PMNs was measured by means of chemiluminescence (CL) method. The CL values of PMNs in tested urines were 1/30 that of phosphate buffer solution. However, PMNs generated O2- at maximum levels when the urine osmolarity was 300-400 mOsm/kg. Furthermore, PMNs did not generate O2- when the urine osmolarity was more than 600 mOsm/kg, or less than 200 mOsm/kg. We also investigated the influence of urea and creatinine on O2- generation of PMNs. The O2- generation of PMNs decreased when the urea concentration rose. However, there was no influence of creatinine on O2- generation of PMNs. From these results, it was elucidated that PMNs generated O2- when the urine osmolarity was 300-400 mOsm/kg. Therefore, urine osmolarity of the patients with urinary tract infection should be kept at 300-400 mOsm/kg, and diuresis might be important for the patients with urinary tract infection.