Posttransplant tubulointerstitial nephritis: clinicopathological correlation

Area of Science:

• Nephrology
• Transplantation Immunology
• Pathology

Background:

• Tubulointerstitial nephritis (TIN) is a recognized cause of renal allograft dysfunction, ranking third after rejection and cyclosporine toxicity.
• Acute TIN was identified in 8% of renal transplant biopsies, indicating its clinical relevance.

Purpose of the Study:

• To investigate the incidence, causes, and outcomes of acute tubulointerstitial nephritis in renal transplant recipients.
• To determine the association between TIN, urinary tract infections, and graft survival.

Main Methods:

• Retrospective analysis of 540 needle biopsies from 280 renal transplant patients (1996-1999).
• Identification of acute TIN and its etiologies (bacterial, cytomegalovirus, granulomatous infections).
• Correlation of TIN with rejection episodes, urinary tract infections (UTIs), chronic allograft nephropathy, and graft loss.

Main Results:

• Acute TIN was diagnosed in 23 patients (8%), primarily due to bacterial infections (17 patients) or cytomegalovirus (CMV) (3 patients).
• Urinary tract infection episodes significantly correlated with chronic allograft nephropathy (P = .03) and graft loss (P < .01).
• Graft loss occurred in 52.2% of patients within 5 years; CMV and granulomatous TIN had poorer outcomes than bacterial TIN.

Conclusions:

• Tubulointerstitial nephritis plays a significant pathological role in renal allograft deterioration and graft loss post-transplantation.
• Infections causing TIN, particularly CMV and granulomatous types, are associated with accelerated graft failure.
• Managing UTIs and identifying TIN etiologies are crucial for improving long-term renal allograft survival.