Abstract

Introduction: Renal-transplant patients with stable graft function and proximal tubular dysfunction (PTD) have an increased risk for IF/TA. The morphological features associated with this dysfunction are unknown. Material and methods: 54 renal transplant patients with normal and stable renal function were submitted to a biopsy and had urinary retinol binding protein (uRBP) and renal function assessment. Patients were divided according to uRBP levels: 1, these findings had no association with uRBP levels. Megalin expression was observed at BB of PTC, 13.7% of bxs presented its expression in less than 50% of tubules, 56.8% had in more than 50% of tubules but with discontinuity over the BB and in 29.5% megalin expressed in more than 50% of tubules continuouslly over the BB. Patients who presented uRBP > 0.6 mg/L had lower amount of megalin expression in their biopsies, p=0.007. Cellular RBP expression was observed diffusely over the cytoplasma of PTC, with different intensities. No correlation was found between tubular megalin expression and uRBP values with CRBP expression. Conclusions: Half of renal transplant patients with normal renal function had PTD. The deficiency of megalin expression could be the subjacent functional alteration found in patients with PTD.

Keywords: Retinol binding protein; Proximal tubular function; Kidney transplantation; Tubulointerstitial injury; Chronic allograft; Nephropathy; Allograft renal biopsy