Immune responses in Mycoplasma pneumoniae infections.

All children with Mycoplasma pneumoniae infection showed a significant response in IgG immunofluorescent (IMF) antibody titers, which were similar to that of complement-fixing (CF) antibody titers. However, there was a certain degree of variation in IgM IMF antibody response and its persistence. This variation also occurred in cases with pre-existing specific antibodies and good CF and IgG IMF antibody titers. Thus, it was considered that a reinfection with M. pneumoniae might not have an important effect upon the individual variation in IgM immune response, and that after a secondary immune response with M. pneumoniae infection with specific IgM antibody could be detected in some patients.