Cell mediated rejection revisited: Past, current, and future directions

Area of Science:

• Nephrology
• Immunology
• Histopathology

Background:

• The Banff classification is the standard for diagnosing kidney allograft dysfunction due to immune reactions.
• It has evolved significantly since 1993, with key revisions in 2007, 2015, and 2017.
• These updates address T-cell-mediated rejection (TCMR) and antibody-mediated rejection.

Observation:

• The Banff classification initially focused on four categories for cell-mediated rejection: interstitial inflammation (i), tubulitis (t), endoarteritis (v), and transplant glomerulitis (g).
• Subsequent revisions introduced scores like total inflammation (ti) and specific interstitial fibrosis/tubular atrophy inflammation (i-IF/TA).
• The Banff 2015 and 2017 schemes established a working group for TCMR and revised criteria for chronic active TCMR.

Findings:

• Chronic interstitial inflammation is recognized as a key factor in poor kidney allograft outcomes.
• Current histological criteria struggle to differentiate immune-mediated injury from non-specific injury in chronic tubulointerstitial inflammation.
• Evolving theories on vascular lesions blur the lines between antibody-mediated and T-cell-mediated injury.

Implications:

• Further research is needed to refine histological criteria for interstitial inflammation and vascular lesions in kidney allografts.
• Improved diagnostic accuracy will lead to more precise therapeutic decisions for transplant recipients.
• Understanding these nuances is crucial for advancing the management of T-cell-mediated rejection.