The difference in histopathology of antibody-mediated rejection between ABO incompatible and pre-sensitized cases

Suppression of antibody-mediated rejection (AMR) is mandatory for the acceptance of renal allograft in ABO blood type incompatible and pre-sensitized combinations. The aim of this study was to evaluate the difference in histopathology of AMR between ABO incompatible (ABOI) and pre-sensitized cases. Among 69 kidney recipients who underwent transplant surgery at our institute since 2002, four patients who manifested AMR were included in this study. They initially received quadrant immunosuppressants, tacrolimus, mycophenolate mofetil, methylprednisolone and basiliximab. Two patients received grafts from ABOI donors and the other two received grafts from flow T-cell crossmatch-positive donors. Although satisfying antibody removal was achieved by pre-transplant plasmapheresis, all four cases manifested acute AMR, within two wk post-transplant. Antibody titer and panel reactive antibody increased at the time of AMR. ABOI cases showed slight cellular infiltration. These cases showed diffuse, strong and linear deposition of C4d at peritubular capillaries (PTC). On the other hand, pre-sensitized cases showed more intense cellular infiltration, especially in glomerulus but only faint and focal deposition of C4d at PTC. All four cases were treated with corticosteroid pulse therapy in conjunction with several sessions of plasmapheresis.