The role of lymphocyte-dependent antibody in kidney transplantation.

The lymphocyte-dependent antibody (LDA) assay has been used in parallel with the microlymphocytotoxicity test detecting complement-dependent antibody (CDA) in 100 cadaver kidney transplant recipients, in order to assess the role of the LDA phenomenon in the rejection of human allografts. In 15 cases, acid eluates were prepared from the kidney graft after rejection or at autopsy and tested in parallel with pre- and post-transplantation sera. The results indicate a marked increase in sensitivity of LDA assay compared with the standard microlymphocytotoxicity test. In 12 patients the pretransplant serum was found retrospectively LDA positive, but CDA negative, using the kidney donor lymphocytes or allogeneic lymphocytes bearing the same incompatible antigen(s) for the recipient as targets. Ten of them lost their graft, mostly during the first month after transplantation. Graft survival was also poor in the 11 patients having both LDA and CDA activity in their pretransplant serum, even when the specificity of the serum did not appear to be directed against antigens shared by the donor. Although it is not clear yet, whether the two assays detect the same or different antibody molecules, it appears that the detection of even a low level of LDA activity before transplantation is associated with a high risk of early transplant failure.