Local Cellular Immune Response in Ascending Urinary Tract Infection: Occurrence of T-cells, Immunoglobulin-producing Cells, and Ia-expressing Cells in Rat Urinary Tract Tissue

The local immune response was studied in rats with ascending urinary tract infection that was induced by Escherichia coli 06K13H1 . The occurrence in urinary tract tissue of cells reacting with monoclonal antibodies to T-cell markers and Ia antigen and with antibodies to immunoglobulin G (IgG), IgM, and IgA was studied by immunohistochemical methods. Serum antibody response and antibody coating of bacteria in the urine were also followed. Infection increased the number of irregular Ia-expressing cells in both bladder submucosa and the intertubular space in the kidney. The epithelial cells of some tubules were induced to express Ia antigens. A slight increase of what were most probably T-"helper" cells in the bladder was noted during the initial phase of infection. These cells soon disappeared, and there was instead an increase in irregular W3/25-reactive cells that may be identical to the observed Ia-positive cells. In the pyelonephritic lesions there were large amounts of T-cells, mainly T-helper cells, Ia-expressing cells, both rounded and irregular, and also IgG-and IgM-producing cells. IgA-producing cells were demonstrated in the infected bladders. The results indicate that distinct differences exist between the immune reactions in bladder and kidney tissue which may be important for the development of infections in these organs.