Peritubular capillaritis (ptc) is a widely accepted histologic criterion of antibody-mediated rejection (ABMR), and while the ptc score is incorporated in current diagnostic recommendations, the utility of subcharacterization of ptc, according to ptc extent and predominance of leukocyte populations is under debate. Recent publications have highlighted the clinical relevance of diffuse ptc extent (> 50% of the cortical renal tissue) as an independent risk factor for inferior clinical outcomes. The current study assesses the relevance of ptc subcharacterization (ptc score, extent and leukocytic subpopulation) in recipients with donor-specific antibody (DSA). Methods: Our study is a secondary analysis of a prospective trial (BORTEJECT,-NCT01873157), including 86 out of 741 stable transplant recipients subjected to cross-sectional antibody screening (≥6 months post transplantation). Based on DSA detection [mean fluorescence intensity (MFI) threshold >1,000], study patients underwent protocol biopsy (Evaluation according to Banff 2013 scheme). The primary endpoint was the chronic lesion score (CLS=cg+ct+ci+cv) in relation to ptc subgroups. Results: Ptc was present in 42 of 86 patients. Ptc scores 1, 2, and 3 were present in 36%, 55% and 9 % while focal ptc and diffuse ptc were found in 36% vs. 64%. Lymphocytes were the dominant leukocytic subpopulation (76%). There were no significant differences regarding DSA HLA class specificity, IgG MFI maximum or sum between the ptc subgroups. CLS were significantly higher in recipients with diffuse ptc extent (6.74 ±2.3, p=0.002), ptc score 2 (6.34 ±2.7; p=0.004) and mixed (lymphocytic + granulocytic) ptc (7.2+±2.0; p=0.02) vs. no ptc (4.4±2.9). Ptc extent and ptc score showed no significant interaction (p=0.6). In linear regression models adjusted for timing of biopsy, C4d, glomerulitis and DSA MFI sum, diffuse ptc extent was independently related to higher CLS even after adjustment for glomerulitis (p=0.02), while ptc score 2 and mixed ptc lost their significant association. Conclusion: Our results suggest clinical relevance of reporting ptc extent in late ABMR cases and further emphasize the role of diffuse ptc extent as a risk factor for chronic damage in kidney allografts.

CITATION INFORMATION: Kikić Z, Eskandary F, Herkner H, Oberbauer R, Bond G, Regele H, Böhmig G, Kozakowski N. Diffuse Extent of Peritubular Capillaritis in Late Antibody Mediated Rejection Is Associated with More Severe Chronic Allograft Damage. Am J Transplant. 2016;16 (suppl 3).

« Back to 2016 American Transplant Congress