IgG, IgA and IgM responses in acute rubella determined by the immunofluorescent technique.

The indirect immunofluorescent technique has been used to study the specific immunoglobulin responses in twelve adult cases of acute uncomplicated rubella. IgG, IgA and IgM antibodies increased virtually simultaneously. IgG antibody persisted throughout the period of study but showed a slight tendency to fall in titre after 7 months. IgM antibody was detected in nine cases. In these patients it was present in high titre 5-15 days after the rash but was not detected after 20 days. IgA antibody was detected in all cases. It was present in high titre 5-20 days after the rash but was no longer detectable after 29 days except in one patient who had a very low titre at 78 days. The presence of specific IgA and IgM indicates recent rubella in uncomplicated cases, and if the immunofluorescent method is used both types of antibody should be sought.