HIGH PREVALENCE AND USUAL PERSISTENCE OF SERUM MONOCLONAL IMMUNOGLOBULINS EVIDENCED BY SENSITIVE METHODS IN RENAL-TRANSPLANT RECIPIENTS

Background. The occurrence of serum monoclonal immunoglobulins in kidn ey transplant recipients is well known but their significance and pred ictive value for the occurrence of lymphoma are a matter of debate. We therefore conducted a study of monoclonal immunoglobulins by a sensit ive method during the long-term follow up of grafted patients. Methods . Monoclonal immunoglobulins were characterized by high-resolution ele ctrophoresis, conventional immunoelectrophoretic analysis, and EI sens itive Western blotting procedure in the serum from 84 renal transplant recipients prior to grafting and subsequently, with a 1-8-year follow -up and excluding the patients who developed posttransplant lymphoma. Results. Low abundance monoclonal immunoglobulins were detectable prio r to transplantation in 56 cases (66.6%) and after graft in 72 cases ( 85.5%) (and in 1 case (1.2%) and 18 cases (21.4%) of cases respectivel y, by immunoelectrophoresis). These abnormalities were often multiple in individual sera. Monoclonal components detected by immunoblotting w ere transient in 23.8% of patients only (whereas those evidenced by im munoelectrophoresis usually became undetectable by this method) and th eir pattern was remarkably stable in the majority of cases. The freque ncy of posttransplant monoclonal immunoglobulins was higher in patient s of more than 50 years of age than in younger patients. The appearanc e of monoclonal components after grafting and their transient characte r correlated with CMV infections. No correlation was found with variou s other parameters. The isotypic distribution of monoclonal immunoglob ulins with an IgM, IgG3, and IgG1 predominance and an abnormally low k appa/lambda, ratio was the same as that observed in various immundefic iency states. The monoclonal immunoglobulin pattern in three further p atients who developed posttransplant lymphoma was unremarkable. Conclu sion. Monoclonal immunoglobulins hence are not discriminant for lympho ma and their characterization does not appear to be necessary in the e valuation of followed up grafted patients, at least for a prediction o f post-transplant lymphoma.