IgG from Epstein-Barr virus infectious mononucleosis patients inhibits interleukin-2 production.

Patients with Epstein-Barr virus (EBV)-associated dissorders usually demonstrate evidence of immunosupression during active disease. Sera of some patients with EBV-induced infectious mononucleosis (IM), contain an IgG-blocking factor (IM-IgG) which inhibits in vitro cell-mediated immune responses and which we postulate plays an important role in viral immunosuppression. We had shown earlier that Isoprinosine (an immunostimulator) has a counterinhibitory effect on this IM-IgG activity. Here we describe evidence showing for the first time that the immunosuppressive activity of IM-IgG is aimed at inhibition of interleukin-2 (IL-2) synthesis and does not affect IL-2 receptors.