Impact of mesangial IgA deposits in 14th‐post operative‐day routine renal allograft biopsies

Abstract

SUMMARY: Three hundred fourteen 14th‐postoperative‐day routine renal allograft biopsies were evaluated together with clinical data. Out of 314 biopsies, mesangial IgA deposits were positive in 122 biopsies (39%). According to Banff classification, the rate of acute rejection was significantly lower in mesangial IgA deposit‐positive (IgA(+)) patients (7.4%) than in mesangial IgA deposit‐negative (IgA(‐)) patients (19.7%) on the 14th postoperative day. Thereafter, rate of biopsy‐proven and clinical acute rejection was continuously lower for up to 12 months in IgA(+) patients than in IgA(‐) patients. The detection rate of mesangial IgA deposits was significantly higher in human leucocyte antigen (HLA)‐well‐matched (HLA mismatch number was <3) patients than in HLA‐poorly matched (HLA mismatch number was ≥3) patients. In HLA‐well‐matched patients, the serum creatinine levels were significantly lower in IgA(+) patients than in IgA(‐) patients after 3 post‐transplant months and up to 1 post‐transplant year. Follow‐up (mean interval: 13 months) allograft biopsies were performed in 34 patients out of 122 IgA(+) patients. In the follow‐up biopsies, initially detected mesangial IgA deposits had disappeared in 22 patients (65%) out of 34 patients. Twelve patients (35%) still had mesangial IgA deposits, and all of them had clinical and pathological findings consistent with IgA nephropathy. Patients with continuous mesangial IgA deposits in the follow‐up biopsies had a better renal function at 1 year and a higher 5‐year graft survival rate compared with patients who lost the initially deposited IgA. The present study demonstrates that long‐lasting mesangial IgA deposits in renal transplants prevent allografts from acute rejection, which leads to better graft outcome.