Immunoglobulin-coated bacteria on the tonsillar surface during infectious mononucleosis.

Sequential bacterial samples were obtained from the tonsillar surface of 19 consecutive patients (12 females, seven males; mean age 16.1 years, range four to 24 years) suffering from infectious mononucleosis with membranous tonsillitis. The specimens were examined with respect to aerobes (culture on blood and chocolate agar plates) and proportions of bacteria coated with immunoglobulins (secretory IgA, IgG, IgM) by using an immunofluorescence assay. In the early stage of the membranous tonsillitis phase, attachment of secretory IgA (SIgA) and IgG to the bacteria was greatly suppressed, as compared with healthy controls. Coating with IgM was evident only late in the membranous tonsillitis phase but was contracted and still evident even after the clinical throat symptoms had abated. The findings suggest that the B-lymphotropic Epstein-Barr virus, causative agent of infectious mononucleosis, exerts a transient suppression of immunoglobulin-coating of bacteria harboured on the tonsillar surfaces, with consequent abundant bacterial attachment to the epithelial cells and massive bacterial colonization on the palatine tonsils.