AFLUID May 45/5

Rice, James C., Jeff S. Spence, Judit Megyesi, Randall M. Goldblum, and Robert L. Safirstein. Expression of the polymeric immunoglobulin receptor and excretion of secretory IgA in the postischemic kidney. Am. J. Physiol. 276 (Renal Physiol. 45): F666–F673, 1999.—The humoral mucosal immune response of the kidney involves the transport of secretory IgA (S-IgA) through renal epithelial cells by the polymeric immunoglobulin receptor (pIgR). The pIgR is cleaved and released as free secretory component (FSC) or attached to IgA (S-IgA). We examined the effects of an ischemic model of acute renal failure (ARF) on the expression of pIgR and the secretion of FSC and S-IgA in the urine. Kidney pIgR mRNA levels decreased in ischemic animals by 55% at 4 h and by 85% at 72 h compared with controls. pIgR protein expression in the medullary thick ascending limb (TAL) decreased within 24 h and was nearly undetectable by 72 h. Urinary S-IgA and FSC concentrations decreased by 60% between days 3 and 6. pIgR mRNA and pIgR protein in the kidney returned to ,90% of control levels and urinary FSC and S-IgA concentrations returned to ,55% of control levels by day 7. We demonstrate that ischemic ARF decreases renal mucosal S-IgA transport in vivo and may contribute to the increased incidence of urinary tract infections.