Local immune response in experimental pyelonephritis in the rabbit. I. Morphological and functional features of the lymphocytic infiltrate.

The cellular activity of circulating lymphocytes and lymphocytes isolated from the infected kidney of animals with experimental haematogenous pyelonephritis was evaluated. The incorporation of [3H-methyl]thymidine into DNA by lymphocytes was studied with mitogens such as phytohaemagglutinin (PHA), pokeweek mitogen (PWM) and goat anti-rabbit IgG (GARIG). Lymphocytes from infected kidney had a high baseline DNA synthesis compared to circulating lymphocytes from days 5 to 27 of infection. Infected kidney lymphocytes failed to respond to PHA, PWM, or GARIG, whereas circulating lymphocytes did respond to these mitogens. Uropod-bearing lymphocytes, which were shown to be T lymphocytes, were present from days 5 to 77 of infection. B lymphocytes, as determined by surface immunofluorescent technique, were present by day 12, coincident with the onset of local synthesis of antibody. These studies reveal that in pyelonephritis, the cellular response goes through sequential changes and indicate a dynamic interrelationship between T and B lymphocytes at an infected site.