Hahn DL, Anttila T, Saikku P.
Epidemiol Infect 1996; 117:513-517***
Due to use of a polyvalent (mixed) antibody, the initial studies could not distinguish whether asthma was associated with C. pneumoniae IgG antibodies, IgA antibodies, or both.
This study found that new-onset adult asthma was associated with IgA but not with IgG. Since IgA is thought to be an indicator of chronic infection in other bacterial diseases, this appears to be the first evidence that IgA might be a marker for chronic infection in asthma.