Urinary secretory immunoglobulin A in acute renal allograft rejection

Periodical determinations of the urinary secretory immunoglobulin A (S-IgA) excretion rate were performed in 12 cadaveric graft recipients. In five patients with primary functioning grafts the S-IgA excretion on the first postoperative day was 4.2 +/- 2.6 mg/g creatinine, decreasing to 1.8 +/- 1.2 mg/g creatinine (P less than 0.05) at the day of discharge. Acute tubular necrosis developed in the seven remaining patients. In this group the initial S-IgA excretion was 12.6 +/- 7.5 mg/g creatinine (P less than 0.05 compared to the former group), decreasing to 2.0 +/- 0.9 mg/g creatinine (P less than 0.05) at discharge. An acute rejection episode was observed in six patients. The S-IgA excretion increased from 3.0 +/- 1.5 mg/g creatinine 3-4 days before rejection to 6.4 +/- 3.1 mg/g creatinine (P less than 0.05) 1-2 days before rejection, and peaked at 14.0 +/- 8.6 mg/g creatinine (P less than 0.05) when the diagnosis of rejection was established and anti-rejection treatment was started. In three patients the initial steroid pulse therapy was not successful and S-IgA excretion further increased to 29.0 +/- 15.6 mg/g creatinine. After successful anti-rejection treatment, using steroids and OKT3, the S-IgA excretion decreased to 3.4 +/- 2.6 mg/g creatinine. In acute graft rejection, the elevated globulin synthesis by infiltrating plasma cells. In the early phase of rejection, dimeric IgA is the only immunoglobulin able to penetrate into the urine by transepithelial transport after binding to secretory component expressed on tubular epithelial cells.(ABSTRACT TRUNCATED AT 250 WORDS)