Studies of the local immune response to pyelonephritis in the rabbit.

The presence of antibody-forming cells in kidney, spleen, bone marrow, and thymus of animals with pyelonephritis was determined with a modified procedure for hemolysis in gel. Antibody-forming cells in the kidney were confined to areas with histological evidence of pyelonephritis. Antibody also accumulated in the renal pelvis. Although conventional agglutination procedures did not demonstrate the presence of urinary antibody, both IgM and IgG antibody to bacteria could be found in the urine during renal infection when a biological amplification system was used. In contrast to previous studies with the rabbit model, the present studies have found IgM to be the predominant antibody synthesized in both the spleen and the pyelonephritic kidney. Maintenance of levels of antibody in serum during chronic pyelonephritis in the rabbit did not depend on continued synthesis of antibody within the kidney or spleen. Removal of the antigenic stimulus by nephrectomy of the pyelonephritic kidney likewise did not affect subsequent levels of circulating antibody. Although antibody has been found in the urine of patients and animals with pyelonephritis [1-3], it has not been clearly established whether urinary antibody is derived from antibody in serum or, more significantly, from local synthesis within the kidney itself. The capacity of the kidney to synthesize antibody was first suggested by Cotran [4], who used fluorescent-antibody techniques to demonstrate antibody-forming cells in the kidney of animals with pyelonephritis. These experiments were extended by Lehmann et al. [5], who demonstrated increased synthesis of immunoglobulins by the kidney in rabbits with experimental renal infections. Subsequent studies have described a protracted local immune response that persisted after the general immune response had subsided in both rabbits and rats [6, 7]. If such locally synthesized