FLOW CROSS-MATCHING IDENTIFIES PATIENTS AT RISK FOR POSTOPERATIVE ELABORATION OF CYTOTOXIC ANTIBODIES

Background, Cytotoxic IgG against class I antigens can contribute to r enal dysfunction or failure after transplantation. However, the clinic al relevance of IgG measured by flow cytometric cross-matching is cont roversial, This study correlated pre-and postoperative flow reactivity with clinical outcome among renal transplant patients with negative p reoperative cytotoxic cross-matches, Methods, Nonsensitized primary re nal allograft patients (n=157) with negative preoperative cytotoxic cr oss-matches (complement-dependent lymphocytotoxicity assays) were stra tified on the basis of IgG reactivity measured by flow cytometric cros s-matching (FCXM) as FCXM negative (Neg) or positive against class I ( T-pos FCXM) or class II (B-pos FCXM) antigens, The groups were compare d in terms of frequency of early rejection and 1-year graft survival, Results, Patient distribution was 67% Neg, 14% T-pos FCXM, 14% B-pos F CXM, and 5% IgM FCXM. The incidence of early rejection was 25+/-3% for Neg and 51+/-3% for T- and E-pos FCXM (P<0.05), One-year graft surviv al for Neg versus T-pos and B-pos FCXM was 97+/-3% versus 44+/-10% (P< 0.05) and 77+/-5% (P=0.06), respectively, Rejections requiring plasmap heresis were found only among patients with T-pos FCXM. Among 29 patie nts, FCXM and complement-dependent lymphocytotoxicity assays were perf ormed 10+/-2 and 28+/-4 days after transplantation. Pre- and posttrans plant antibody levels were relatively unchanged among Neg and B-pos FC XM patient groups. In contrast, patients with T-pos FCXM produced cyto toxic IgG against class I after transplantation, which may have contri buted to the severe graft dysfunction experienced by this group, Concl usions. FCXM is a useful tool to stratify primary renal transplant can didates in terms of potential risk for severe rejection, Furthermore, demonstration of preoperative flow reactivity against class I may iden tify a subgroup of patients at risk for early elaboration of cytotoxic alloantibody.