Oligo-monoclonal immunoglobulins frequently develop during concurrent cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections in patients afterrenal transplantation

In the present study we report that the appearance of oligo-monoclonal immu noglobulins (oligoM-Igs) in the sera of transplanted individuals is concurr ent with the detection of coincident active CMV infection and EBV replicati on. Eighty-four renal allograft patients were monitored with respect to CMV isolation, to CMV conventional serology and humoral response against the E BV trans-activator ZEBRA (an immediate-early antigen also called BZLF1). Ti tration of anti-ZEBRA antibodies (IgG and IgM) and amount of EBV DNA in ser um were evaluated. Using the combination of four techniques (agarose gel el ectrophoresis, analytical isoelectric focusing, high resolution immunoelect rophoresis, immunofixation electrophoresis), oligoM-Igs were found in 25% o f patients after allografting and significantly associated with rejection e pisodes (P < 0.001). Twenty out of 23 (86%) concurrent CMV/EBV infections w ere associated with serum oligoM-Igs (P < 0.001). One can thus reasonably a ssume that a sustained EBV replication following iatrogenic immunosuppressi on can promote the immunoglobulin heavy chain expression in EBV-infected B lymphocytes. The proliferation of immunoglobulin-secreting clones might occ ur after active CMV infection, through a transient over-immunosuppression o r via immune subversion.