*Purpose: The diagnosis of antibody-mediated rejection (ABMR) in renal allografts requires microvascular inflammation in the form of glomerulitis or peritubular capillaritis (g>0 and/or ptc>0). We investigated whether outcomes of glomerulitis-predominant ABMR (g-ABMR) and peritubular capillaritis-predominant ABMR (ptc-ABMR) differ from other forms of ABMR.

*Methods: All patients diagnosed with ABMR per the 2017 Banff classification from 1/2008 to 12/2017 at our center were included. Biopsies with a g+ptc score of ≥2 and a difference of at least 2 points between the g score and ptc score were considered g-ABMR (g=3/ptc=0 or 1; g=2/ptc=0 ) or ptc-ABMR (ptc=3/g=0 or 1; ptc=2/g=0). Graft survival and change in eGFR over time were compared to a control group of patients with ABMR with a g+ptc score ≥2 and a difference in the g- and ptc-scores of <2.

*Results: Ten biopsies with g-ABMR and 25 with ptc-ABMR were compared to 43 controls. Patients were younger and time to diagnosis was longer in the ptc-ABMR group compared to g-ABMR (table 1). High DSA MFI was more commonly seen in patients with ptc-ABMR. Graft survival at 4.5 years was 100%, 65.1% and 52.0% in g-ABMR, ptc-ABMR and control groups respectively (Log rank p=0.35) (fig 1). There was a statistically significant decline in eGFR slope in the ptc-ABMR group whereas eGFR slope was not statistically different than zero in the control and g-ABMR groups (fig 2).

*Conclusions: ptc-ABMR was associated with a more significant decline in kidney function. The presence of strong binding DSA could be a confounding factor in decline of allograft function observed in the ptc-ABMR group, but could not be accounted for in this preliminary study.

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