C4d deposition in peritubular capillary and alloantibody in the allografted kidney suffering severe acute rejection

Background: Alloantibodies and C4d deposition in peritubular capillaries (PTCs) are thought to be related to antibody-mediated acute rejection. The purpose of this study was to evaluate the relationship between C4d deposition in PTCs and alloantibodies at various days after allograft dysfunction due to severe acute rejection. Method: There were 620 renal transplantations (Tx) performed. Forty patients diagnosed with acute humoral and/or vascular rejection showed graft dysfunction with anuria or dysuria. The patients were divided into four groups by ABO compatibility and clinical course after graft dysfunction: compatible recipients with graft loss (c-GL; n = 6); compatible recipients with recovery from graft dysfunction (c-RE; n = 10); incompatible recipients with graft loss (i-GL; n = 9); and incompatible recipients with recovery from graft dysfunction (i-RE; n = 15). Results: C4d depositions in 4/6 c-GL recipients increased, and those in 8/10 c-RE recipients decreased after graft dysfunction. These changes in C4d deposition between the c-GL and the c-RE groups were significantly different (P < 0.01). These titres of anti-A/B IgG antibody in 7/9 i-GL recipients increased and those in 8/15 i-RE recipients decreased after graft dysfunction. These changes in titre between the i-GL and the i-RE groups were significantly different (P < 0.01). All c-GL recipients and 4/10 c-RE recipients had anti-HLA antibody at the last biopsy. There was a significant difference in the number of recipients who had anti-HLA antibody between the c-GL and the c-RE groups (P < 0.05). Conclusions: These results indicate that changes in C4d deposition in PTCs in the c-ABO group and titre of anti-A/B IgG antibody in the ABO-incompatible groups exert a strong impact on graft survival after dysfunction in the early period after Tx.