Antibody-mediated vascular rejection of kidney allograft: characterization of different kidney allograft rejection phenotypes via histology, C4d deposition and donor-specific antibodies

Clearance of Intra-graft Donor Specific Anti-HLA Antibodies in the Early Stage of Antibody-Mediated Rejection Following Rituximab and Apheresis Therapy in Renal Transplantation

BACKGROUND

The management of acute or, in particular, chronic antibody-mediated rejection (AMR) resulting from donor-specific HLA antibodies (DSA) is a critical barrier to obtaining better long-term graft survival. To ascertain the efficacy of anti-AMR therapies, the transition of intra-graft DSA (g-DSA) was assessed.

METHODS

Allograft biopsy specimens were analyzed by graft immunocomplex capture fluorescence analysis, as previously described. One hundred recipients who underwent graft biopsies between April 2016 and December 2017 were enrolled for this study. Fifteen recipients diagnosed with g-DSA positive (+) received anti-humoral treatments and underwent follow-up biopsies. g-DSA levels were assessed again by a follow-up biopsy at 6-12 months following the treatments.

RESULTS

With anti-humoral treatments, 9 out of 15 recipients comprised a g-DSA negative (-) (3.59 ± 2.82-.58 ± .25): g-DSA6-12- group, while the remaining 6 recipients comprised a g-DSA +(20.6 ± 17.0-14.9 ± 14.1): g-DSA6-12+ group. The initial g-DSA scores were significantly higher in the g-DSA6-12+ group (P = .01). All samples were diagnosed as chronic AMR in the g-DSA+ groups, whereas there were 3 chronic AMR, 4 acute AMR, and 2 incomplete AMR samples in the g-DSA- group. Interestingly, the frequency of responsible DSA belonging to class II tended to be higher in the g-DSA6-12+ group (4/6) compared to the g-DSA6-12- group (2/9) (P = .14).

CONCLUSION

These results imply that chronic exposure to DSA causes significant and irreversible damage to the allograft. Timely and adequate anti-humoral intervention might reverse the early phase of AMR with complete clearance of g-DSA.