Endothelialitis without Tubulointerstitial Infiltrates in Renal Transplant Biopsies: Histological Findings, Clinical and Prognostic Relavance

Abstract

Introduction: In order to avoid unnecessary therapy it is currently debated, whether acute cellular rejection with Banff components v≥1, i0, t0 (v_only) has the same therapeutic and prognostic implications as acute cellular rejections with Banff components v≥1, i≥1, t≥1 (v_plus). We examined this question retrospectively in renal transplant biopsies from a single center. Methods: All 23 renal transplant biopsies (from 23 patients) from our biopsy archive with v_only were retrospectively compared to 23 biopsies from 23 patients with v_plus. All patients, v_only and v_plus, received therapy for acute cellular rejection. They were then followed for 135 weeks ±106 (v_only) or 201 weeks ± 151 (v_plus). Results: No significant difference was found between v_only and v_plus regarding donor sex, donor age, immunosuppressive regimen, recipient age, time between transplantation and biopsy, number of glomeruli in the biopsy, Banff components v, g, mm, ah, cg, cv, ci, ptc, ratio of of preglomerular vessels with endothelialits to sum of preglomerular vessels, C4d-positivity of preglomerular endothelium, of peritubular capillary endothelium (Banff C4d), of glomerular endothelium, eGFR at biopsy, type of anti-rejection therapy, eGFR one week after initiation of anti-rejection therapy, eGFR slope per week between biopsy and end of follow-up.v_only had significantly more HLA-mismatches, a higher Banff ct component and and less cortical tubular interstitial edema. Conclusion: Our data show marginal histological differences between v_only and v_plus (with the exception of the defining Banff components i and t). We could not find a difference regarding response to anti-rejection therapy, transplant function or prognosis between v_plus and v_only. The higher number of HLA-mismatches in v_only might suggest, that this rare diagnosis could be associated with donor specific antibodies. We will examine this possible association further in our cohort.