Humoral immune response in Epstein-Barr virus infections. I. Elevated serum concentration of the IgG1 subclass in infectious mononucleosis and nasopharyngeal carcinoma.

Using radial immunodiffusion we measured IgG subclass concentrations and studied their distribution in serum samples from patients with infectious mononucleosis (IM) and nasopharyngeal carcinoma (NPC), two Epstein-Barr virus (EBV)-associated diseases, in comparison with two control groups [completely anti-EBV negative persons and subjects carrying antibodies to the viral capsid antigen (VCA)]. Antibody titres to VCA and to the early antigen (EA) were determined by indirect immunofluorescence and revealed characteristic patterns for the respective diagnostic groups. Nephelometric assays served for quantitating total protein, albumin, total IgG, IgA and IgM in all the sera. In the IM and NPC groups the concentration of IgG1 was significantly elevated by more than 50% whereas the other three subclasses remained unchanged as compared with the controls. Correspondingly, we found a significant increase of total IgG in IM and NPC. In IM, the only disease where VCA-specific IgM antibodies have been reported to occur, IgM levels were markedly elevated. Our data suggest that the IgG1 subclass plays an important role in the humoral immune response to EBV-determined antigens and that it is possibly involved in the control of virus infection.