Monitoring of B lymphocyte response with the protein-A plaque assay in kidney transplant patients.

The protein-A plaque assay was used for serial monitoring of spontaneous plaque-forming lymphocytes (PFC) in blood or thoracic duct lymph of 30 renal transplant patients. In patients experiencing early or delayed graft rejection, PFC manifested a 10-fold increase over the preoperative or control level within one month of the transplantation. Patients accepting the renal graft did not exhibit a remarkable PFC response. Among the factors examined (proportion of B cells, donor source, acute tubular necrosis, intraoperative blood transfusion, antilymphocyte serum, histocompatibility, and rejection), the PFC response was most closely related to graft rejection. Changes in serum immunoglobulin (Ig) did not appear to correlate with the PFC response. By using Ig-class-specific antisera, secreted Ig was identified as IgG, IgM, and IgA. This may indicate that renal grafts induce polyclonal activation of the recipient's B cells.