Predictive power of ELISA-detected anti-HLA class I antibodies in pediatric kidney transplantation

Human Leukocyte Antigen Antibodies for Monitoring Transplant Patients

Human leukocyte antigen (HLA) antibody-mediated hyperacute rejection has dramatically decreased since the clinical introduction of crossmatch technology. However, the role of HLA antibody in acute and chronic rejection remains unclear. In this article, we cite publications to show the correlation between HLA antibody and allograft rejection. Potential pathological mechanisms of antibody-mediated rejection are also proposed and the rationale of commonly used HLA antibody detection techniques are introduced. The advantages and disadvantages of these technologies are further discussed in detail. We conclude that owing to the recent availability of improved antibody detection methods, a causal relationship between HLA antibodies and allograft rejection is now considered to exist.

Humoral theory of transplantation

According to the humoral theory of transplantation, antibodies cause allograft rejection. Publications are cited showing that antibodies: (1). cause hyperacute kidney rejection, (2). lead to C4d deposits associated with early kidney graft failures, (3). are a good indicator of presensitization leading to early acute rejections, (4). were present in 96% of 826 patients who rejected a kidney graft, (5). are associated with chronic rejection in 33 studies of kidney, heart, lung and liver grafts, and (6). in three studies, appeared in the circulation BEFORE evidence of bronchiolitis obliterans in lung transplants, and BEFORE kidney rejection. In addition, a prospective cooperative study of 1629 patients in 24 centers demonstrated that antibodies foretold subsequent failures after a follow-up period of 6 months (p = 0.05). The specificity of antibodies detected in the serum of rejecting patients were often not donor specific, presumably because they were absorbed by the rejecting organ. If the humoral theory is accepted, even provisionally, transplanted patients who have antibodies could be treated with immunosuppression until the antibodies disappear to determine whether chronic rejection can be blocked. If successful, in patients who do not have antibodies, immunosuppression could be reduced until antibodies appear.

The dynamics of antidonor antibody formation early after clinical kidney transplantation measured by flow cytometry and microcytotoxicity test

To study the dynamics of antidonor sensitization 92 patients were monitored for antibodies against donor T and B spleen lymphocytes before transplantation, within the first month after transplantation and 3 months after transplantation. Patients were monitored for donorreactive antibodies (DRA) of immunoglobulin G (IgG), IgA, and IgM isotype using flow cytometry (FC) and the standard microcytotoxicity test (CYT). Graft function was followed for at least 2 yrs, 51% of patients for 3 yrs after transplantation. Within the first month after transplantation the percentage of patients with antidonor sensitization detected by FC rose dramatically, so that the overall sensitization rate increased from 28 (30.4%) of 92 patients prior to transplantation to 63 (68.5%) of 92 patients after transplantation. Whereas preoperatively only one isotype (IgM for T lymphocytes, IgG for B lymphocytes) and only one target cell type (either T or B lymphocytes) dominated, the postoperative patterns of positive FC results were more variable regarding target and isotype, whereby FC-DRA of the IgA class substantially contributed. Appearance of donor-directed antibodies early after kidney transplantation is a frequent event. In our cases, sensitization with FC-DRA per se seemed not to be detrimental to the graft outcome (p > 0.05) but CYT-DRA did resulting in a significant poor graft outcome 3 months after transplantation (p < 0.001).