Immune checkpoint inhibitors (ICIs) can provide survival benefits to cancer patients; however, they sometimes result in the development of renal immune-related adverse events (irAEs). Tubulointerstitial nephritis (TIN) is the most representative pathological feature of renal irAEs. However, the clinicopathological entity and underlying pathogenesis of ICI-induced TIN are unclear. Therefore, we compared the clinical and histological features of this condition with those of non-ICI drug-induced TIN. Age and C-reactive protein levels were significantly higher in ICI-induced TIN, but there were no significant differences in renal function. Immunophenotyping of ICI-induced TIN showed massive T cell and macrophage infiltration with fewer B cells, plasma cells, neutrophils, and eosinophils. Compared with those in non-ICI drug-induced TIN, CD4+ cell numbers were significantly lower in ICI-induced TIN but CD8+ cell numbers were not significantly different. However, CD8/CD3 and CD8/CD4 ratios were higher in ICI-induced TIN. Moreover, CD25+ and FOXP3+ cells, namely regulatory T cells, were less abundant in ICI-induced TIN. In conclusion, T cell, B cell, plasma cell, neutrophil, and eosinophil numbers proved useful for differentiating ICI-induced and non-ICI drug-induced TIN. Furthermore, the predominant distribution of CD8+ cells and low accumulation of regulatory T cells might be associated with ICI-induced TIN development.
Keywords: immune checkpoint inhibitor; regulatory T cells; tubulointerstitial nephritis.
© 2024 The Authors. Pathology International published by Japanese Society of Pathology and John Wiley & Sons Australia, Ltd.