Local immune response to Escherichia coli pili in experimental pyelonephritis

The local immune response to pili of Escherichia coli O6:K13:H1 was determined in experimental hematogenous pyelonephritis in rabbits. Pili purified from sheared cells by ammonium sulfate precipitation were found to be pure by electron microscopy and negative for lipopolysaccharide by limulus lysate assay. Antipilus antibody was detected in serum and newly synthesized protein from infected animals with enzyme-linked immunosorbent assay. Serum and local (intrarenal) antibodies were of the immunoglobulin G class, were detectable by day 20 of infection, and persisted though 250 days of infection. These data suggest that pili are present on the organism at the site of infection, since they induce the local synthesis of antipilus antibody in experimental pyelonephritis.