Characterization of rejection episodes in patients following positive crossmatch and ABO-incompatible live donor renal transplantation.

For kidney transplant recipients with donor-specific antibody (DSA) to HLA- (+XM) or ABO-antigens (ABOI), there is a need to improve detection and treatment of antibody-mediated rejection (AMR). The methods included a retrospective review of consecutive patients that received plasmapheresis and immune globulin (PPIVIg) to abrogate +XM or ABOI. Twelve patients were transplanted after PPIVIg (+XM = 9, ABOI = 2, +XM/ABOI = 1). No hyperacute rejections occurred. Rejection occurred in seven patients [four AMR, three acute cellular rejection (ACR)]. In four +XM patients, DSA was detected during graft dysfunction despite lack of histologic and C4d features of AMR. In one patient, DSA preceded the histologic and immunofluorescent features of AMR. In another patient with borderline changes and DSA, graft function improved after PPIVIg, despite lack of histologic or immunofluorescent evidence of AMR. One patient with Banff IIA ACR and DSA treated with antithymocyte antibody but not PPIVIg had recurrent rejections and poor graft function. In +XM and ABOI recipients with graft dysfunction: (i) DSA may represent AMR in the absence of C4d or histologic features of AMR; (ii) DSA can precede C4d or light microscopic features of AMR; (iii) A poor outcome may result if DSA or continued allograft dysfunction is present and not treated despite a negative biopsy.