Prevalence of monoclonal immunoglobulins after liver transplantation - Relationship with posttransplant lymphoproliferative disorders

Background. A high incidence of serum monoclonal immunoglobulins (mIgs) has been described after solid organ transplantation. For transplant recipients, the prevalence of posttransplant lymphoproliferative disorders (PTLDs) has been reported to be between 2% and 6%. The relationship between the finding of serum mIg in transplant recipients and the subsequent development of PTLDs is not clearly documented. Methods. We retrospectively analyzed all cases of mIg and PTLD that occurred in 86 liver transplant recipients who survived more than 3 months. Patients were characterized by protein electrophoresis, immunofixation electrophoresis, pre- and post-liver transplantation Epstein-Barr virus (EBV) serology, EBV presence in lymphoproliferative tissues by in situ hybridization, type of infection episodes, rejection episodes, and immunosuppressive treatment. Results. Thirty-eight patients (44%) had abnormal immunofixation electrophoresis with an electrophoretic Ig peak. Twelve patients had a polyclonal Ig peak, and 26 patients had mIgs (30%). These 26 patients were divided into two groups: 13 patients had a transient mIg peak with a mean delay for normalization of electrophoresis of 2 months, and 13 patients had a permanent mIg peak. No correlation could be demonstrated between the appearance of abnormal banding and indications for transplantation, age of patients, and acute rejection rate. There was a strong correlation between occurrence of viral infections and presence of permanent mIg. Three patients with permanent mIg (23%) developed PTLD and died. Conclusions. We concluded that the prevalence of mIg after liver transplantation was 30%. Viral infections increase the risk of developing mIg. Persistence of mIg beyond 7 months may be regarded as prelymphomas necessitating a careful follow-up in these patients.