Tamm-Horsfall protein in reflux nephropathy

The distribution of Tamm-Horsfall protein, the main protein in normal urine, was studied immunohistologically in the kidneys of 70 pigs with unilateral vesico-ureteric reflux but without outflow obstruction. Strains of Escherichia coli were inoculated in the bladder. Inflammatory changes of reflux nephropathy (chronic pyelonephritis) were found in 52 pigs. There were extra-tubular deposits of Tamm-Horsfall protein in the kidneys of only 26 pigs. These deposits were small, increased in prevalence as the size of inflamed areas increased, and were not associated with deposits of the protein in glomeruli. These findings suggest that escape of Tamm-Horsfall protein from tubules and backwash into glomeruli are not major features of low pressure reflux nephropathy, unlike the findings in outflow obstruction of the lower urinary tract. There was no evidence that a reaction to Tamm-Horsfall protein was important in the pathogenesis of reflux nephropathy.