Previous reports have described an increase in arteritis during acute rejection (AR) in angiotensin II type 1 receptor antibody (AT1Rab) positive (ve+) kidney transplant recipients (KTR). This study aimed to analyze the histological findings at time zero (T0), acute rejection (AR), and 12 mo protocol biopsies (Bx) from pre-transplant AT1Rab+ve (without HLA-DSA) kidney transplant recipients (KTR), and in a group of KTR with neither AT1Rab nor HLA-DSA pre-KT. Methods: We previously reported the data from 111 living donor KTR (03/2009 to 08/2012) screened pre-KT for both AT1Rab and HLA-DSA abs. Of 111, 13 (11.7%) tested AT1Rab+ve (>17 IU) & HLA-DSA –ve, and 90 tested –ve for both AT1Rab and HLA-DSA (No Abs). For this study, all graft Bx´s obtained from 13 AT1Rab+ve KTR and 29 AT1Rab-ve/HLA-DSA-ve KTR [control group (CG) paired by donor & recipient age, gender and HLA-match] were blinded, reviewed and graded (Banff 2013) by a nephropathologist. Results: No pathological feature was different between the groups (Index: G, PTC, V, C4d and Cg) except for sub-intimal fibrosis, present in 4/4 AT1Rab+ve pts during AR; this finding persisted in 12mo protocol Bx´s compared to 1/11 AR Bx from a No Abs pt, (p=0.007), Figure 1.

Whether the finding of subintimal fibrosis in 100% of patients who experienced AR having AT1Rab maybe attributed to the effect of the abs deserves to be confirmed in a larger patient population study. Likewise, the potential impact of this vascular alteration in long-term graft outcome should be analyzed.

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