ASSOCIATION BETWEEN DE NOVO DONOR SPECIFIC HLA ANTIBODY, C4D STAINING IN RENAL GRAFT BIOPSY AND GRAFT OUTCOME: A SINGLE CENTER EXPERIENCE.

In 69 renal transplant recipients (RTR), all had a functioning graft (SCr < 2.0) at one year. After one year, transplant dysfunction was observed and these 69 RTR were biopsied, tested for C4d deposition and donor specific antibodies (DSA). Of these 69 RTR, 29 (42%) showed C4d negativity, 27 (39%) were C4d positive and 13 (19%) were not diagnostic. Forty-nine (71%) recipients had HLA antibodies and 41 (59%) had DSA. The proportion of C4d positivity was significantly higher in patients with DSA (HLA Class I only, II only, and I & II) in comparison to patients without post-transplant HLA antibodies. The incidence of graft failure (including current SCr > 4.0) in RTR with HLA Class II antibodies (Class II only or I & II) was significantly higher than in RTR without post-transplant HLA antibodies (P=0.03).Even after amelioration of rejection, the RTR with Class II DSA group continued to fail beyond 2 years after transplantation when compared with the other 2 groups (None/NDSA or HLA Class I only), however, the difference in graft survival between HLA Class II and None/NDSA groups did not reach statistical significance (log-rank P=0.32). Significant association between C4d staining, post-transplant HLA Class II antibodies and graft failure strongly suggests the importance of post-transplant HLA antibodies. HLA Class II DSAs may be an indicator of chronic allograft nephropathy (CAN) proceeding to graft loss. We propose that amelioration of CAN graft loss may be affected by monitoring and identification of DSA with appropriate immunosuppression of these antibodies.