ESPN 54th Annual Meeting

ESPN 2022


 
Evaluation of the significance of isolated C4d staining without histological evidence of rejection on kidney biopsies after ABO-compatible transplantation in pediatric recipients
CHARLOTTE DUNETON 1 MARION RABANT 3 JEAN PAUL DUONG-VAN-HUYEN, 3 VERONIQUE BAUDOUIN 1 ELODIE CHEYSSAC 1 OLIVIA GILLION BOYER 2 JULIEN HOGAN 1

1- PEDIATRIC NEPHROLOGY DEPARTMENT, ROBERT DEBRé HOSPITAL, APHP, PARIS FRANCE
2- PEDIATRIC NEPHROLOGY DEPARTMENT, NECKER ENFANTS-MALADES HOSPITAL, APHP, PARIS FRANCE
3- DEPARTMENT OF PATHOLOGY, NECKER ENFANTS-MALADES HOSPITAL, APHP, PARIS FRANCE
 
Introduction:

C4d staining in peritubular capillaries has been part of ABMR Banff definition since 2003. Despite relatively high specificity, c4d staining shows limited sensitivity, and the clinical significance of C4d+ biopsies without other histological evidence of rejection (WER) is unknown. We aimed to assess the clinical significance of c4d+ biopsies WER on kidney biopsies after ABO-compatible transplantation in pediatric recipients

Material and methods:

We retrospectively analyzed patients under 18 years with c4d+WER biopsies performed between 2011-2020, in 2 pediatric transplant centers in Paris, France. All biopsies were reviewed by a single expert pathologist to confirm the immunohistochemical C4d+ staining and to ensure the absence of ABMR or TCMR. C4d+ WER patients were compared with a cohort of C4d- patients matched on recipients’ demographics, year and center of transplantation, biopsy indication and time to transplantation.

Results:

6% of biopsies were C4d+WER. 40 C4d+WER children were compared with 40 matched C4d- controls (median age 12 and 11,6 years). 65% were protocol biopsies performed within the 1st year after transplant (median 6,9 months, IQR 2,5–15,2). There was no significant difference regarding recipient, donor, or transplant characteristics. However, C4d+ patients showed significantly more DSA on the day of biopsy (40% vs 17,5%, p=0,047). After a 4-years median follow-up, 4/40 C4d+ patients developed an ABMR within year 1 (10,4 months, IQR 6,2–14,0). All these patients were DSA+ at the time of biopsy. However, among the patients who had a follow-up biopsy (n=32), we noted a negativation of C4d staining in 78%, including 20/32 patients (62%) in the absence of specific treatment. Survival rate without ABMR did not differ between C4d+ and C4d- patients (Fig A). However, C4d+ DSA+ patients developed significantly more ABMR within the 1st-year post biopsy compared with C4d+DSA- and C4d- patients (Fig 2). Interestingly, patient characteristics and outcomes of C4d+DSA- patients did not differ from C4d- patients.

Conclusions:

C4d+WER biopsies DSA- do not represent an increased risk of ABMR compared to C4d- patients. Molecular analysis of the biopsies may help to assess the significance and clinical implication of C4d+WER in pediatric kidney transplant recipients.