Nasal immunoglobulin responses in acute rubella determined by the immunofluorescent technique

The indirect immunofluorescent technique has been used to study the specific immunoglobulin responses in nasal secretions from ten adults with acute rubella. Titres of IgA antibody in nasal washings usually exceeded those of IgG, but both types of antibody were detected in all patients. They appeared a few days after the rash, reached maximum titres during the second week and then declined. IgA antibody was no longer detectable after 47 days and was not detected at all in nasal washings from adults who had experienced rubella in the past. Low titres of IgG antibody persisted in some patients for longer than IgA and traces of IgG were found in nasal washings from a minority of adults with a past history of rubella. Nasal antibodies in acute rubella are therefore transient and unlikely to take part in resistance to reinfection.In sucrose-density gradients nasal IgA antibody sedimented more rapidly than IgG and there was little overlap between these two types of antibody. IgA antibody in serum was more heterogeneous; it was found in nearly all the fractions which contained IgG antibody and in many of those which contained IgM.