Kidney allografts with biopsy features of chronic mixed rejection reflect poorer survival than those with pure chronic antibody-mediated rejection D. Dobi, Zs . Bodó, É. Kemény, K. Boda a , P. Szenohradszky b , E. Szederkényi b , B. Iványi Departments of Pathology, Medical Physics and Informatics a and Surgery b University of Szeged, Szeged, Hungary

Introduction

In late dysfunctional kidney allograft biopsies three rejection phenotypes can be observed: • chronic antibody-mediated rejection (AMR) • acute T-cell-mediated rejection (TMR) • chronic active TMR

Chronic AMR: transplant glomerulopathy and/or transplant capillaropathy cg ptcml

Acute TMR: interstitial infiltrates and tubulitis (interstitial rejection, ISR) with or without intimal arteritis

Chronic active TMR: mononuclears in intimal fibrosis (cv mo )

• Frequency: chronic AMR > acute TMR; chronic active TMR is exceptional • Chronic AMR and TMR may concur, termed chronic mixed rejection (CMR)

Objectives

To analyze • the histological patterns of chronic mixed rejection (CMR) • the clinicopathological relevance of the different patterns of CMR

Material and methods

• From 2001 to 2011, 61 biopsies displayed the histological features of chronic AMR (cg and/or ptcml ± C4d-positivity) • Luminex data were not avaible • Re-evaluation according to the Banff scheme (v, g, i, t, ptc, cg, ci,ct, ah) plus • Scoring of chronic arterial changes: mononuclears in intimal fibrosis (cv mo ), intimal fibrosis (cv IF ), intimal fibroelastosis (cv IFE ); and tubular HLA-DR and ptcml

• Staining of chronic active arteritis (cv mo ) cases with CD3 and CD68 in adjacent sections • Two groups for clinicopathological analysis: purely CAMR

vs

CMR • Statistics: Spearman’s correlation, hierarchical cluster analysis, Kaplan-Meier estimator, Cox regression

Results: main clinical data

All patients (n=61) Purely CAMR (n=35) Posttransplant time (months) eGFR (ml/min/1.73 m 2 ) Postbiopsy follow-up (months) 66 ±49 26 ±12 23 ±22 70 28 26 ±49 ±12 ±22 CMR (n=26) 60 23 19 ±49 ±13 ±20

p

ns ns ns

35

Histological patterns

12 4 Purely CAMR Chronic active TMR Chronic active TMR and acute ISR CMR 10 Acute ISR

Features of chronic active arteritis Severe luminal narrowing (median score 3), mononuclears scattered throughout the fibrotic intima, T-cell predominance PAS CD3 CD68

Significant (p<0.05) and positive Spearman correlation coefficients between Banff scores and chronic arterial changes t i 0.769

HLA-DR 0.606

t 0.654

HLA-DR cv mo ptc 0.347

C4d g 0.2750.354

0.363

cv mo cg ptcml cv IF ci ct 0.301 0.264

ah ptc 0.3280.331

C4d 0.303

g 0.338

cg 0.258

ptcml 0.414 0.269 0.263

cv IF ci 0.806 0.299

ct ah cv IFE cv IFE

cv IF cv mo cv IFE Hierarchical cluster analysis

Mean eGFR values in purely CAMR and CMR 25 20 15 50 45 40 35 30 Time before (-) and after (+) biopsy (Bx) (months) purely CAMR CMR

Therapy Steroid pulse Postbiopsy therapy Purely CAMR CMR CAMR (n=35) Chronic active TMR (n=12) Chronic active TMR and acute ISR (n=4) 5 5 4 Acute ISR (n=10) 10 Intensification of maintenance immunosuppression Anti-thymocyte globulin Plasmapheresis Left untreated 8 0 0 22 6 0 0 2 1 2 2 0 0 0 0 0

Mean graft survival in purely CAMR and CMR groups 50

vs

22 months Purely CAMR CMR p=0.011

Multivariable Cox regression of morphological variables HLA-DR g C4d CNI-tox.

cv

mo

cv

IF

ct ptc cg ci t i ptcml cv

IFE

ah

Discussion

I. CMR was frequent in our series (43%) II. Chronic active arteritis appeared to be T cell-related a. T-cell predominance in 14/16 cases b. Clustered with TMR lesions C. Lefaucheur et al. Antibody-mediated vascular rejection of kidney allografts: a population-based study. Lancet 2013; 381: 313-319.

III. CMR was characterized by poorer allograft survival and more reduced allograft function than purely chronic AMR if chronic active arteritis was part of the TMR component IV. The immunohistochemical profiling of chronic active arteritis is recommended