Antilymphocyte Antibodies, Renal Transplantation, and Meta-Analysis

Antibodies directed against human lymphocytes are among the most potent immunosuppressive agents available for organ transplantation [1-6]. These biological preparations, referred to here as antilymphocyte antibodies, vary in the type of cell (lymphocyte, lymphoblast, thymocyte) used to induce the antibody response and the host (horse, rabbit, mouse-human hybridoma) in which the response is induced. When used to treat acute rejection, they improve graft survival. When used as induction therapy immediately after transplantation, they reduce the risk for acute rejection, but clinical trials have not shown them to have a beneficial effect on graft survival, in part because these trials did not have adequate power to assess this outcome.

The use of antilymphocyte antibodies also has disadvantages. These agents may induce an antibody response against the host, which can limit their use to a single course of therapy. They also cause profound immunosuppression that may unleash deadly viral infections or virus-associated lymphomas. The cost of antilymphocyte antibody treatment (several thousand dollars per course) adds substantially to the overall cost of renal transplantation. Thus, the optimal use of antilymphocyte antibodies in renal transplantation is not established, and practice varies considerably among transplantation centers.

Some centers use antilymphocyte antibodies only to treat acute rejection; others use induction therapy in all patients. Still others use induction therapy only in patients at high risk for acute rejection and treat acute rejection as needed in the remaining patients. To clarify the efficacy of induction therapy, Szczech and colleagues [7, 8] have published two articles, one of which appears in this issue. In each of these papers, the authors report results obtained with a different type of meta-analysis used to combine results from randomized, controlled trials. It is worthwhile to compare the methods used in these two studies and to contrast their results.

The first of …