Neutrophil recruitment and resistance to urinary tract infection

This study examined the role of neutrophil leukocytes for the antibacterial defense at mucosal infection sites. Urinary tract infection (UTI) was esta blished by injection into the bladder lumen of Escherichia coli 1177, a ful ly virulent clinical isolate. Infection of C3H/HeN (lps(n), lps(n)) mice re cruited neutrophils into the urinary tract, and bacteria were cleared from kidneys and bladders. The neutrophil response was absent in C3H/HeJ (lps(d) , lps(d)) mice, and bacteria persisted in the tissues. Peripheral neutrophi l depletion of C3H/HeN mice was subsequently achieved by pretreatment with the granulocyte-specific antibody RB6-8C5, The E. coli-induced neutrophil r ecruitment was inhibited, as shown by immunohistochemistry and tissue myelo peroxidase quantitation. As a consequence, bacterial clearance from kidneys and bladders was drastically impaired. Antibody treatment of C3H/HeJ mice had only a marginal effect. The results show that neutrophils are essential for bacterial clearance from the urinary tract and that the neutrophil rec ruitment deficiency in C3H/HeJ mice explains their susceptibility to gram-n egative UTI.