High rate of monoclonal gammopathy among immunocompetent subjects with primary cytomegalovirus infection.

Serum samples from immunocompetent adults with primary cytomegalovirus (CMV) or Epstein-Barr virus (EBV) infection and from solid-organ or bone marrow transplant recipients with primary CMV infection were examined for paraproteins. Several immunocompetent patients with CMV infection but none with EBV infection presented with an M component, which implies that the M component connects CMV infection to a risk of B cell malignancy.