Serologic markers for Chlamydia pneumoniae in asthma.
BACKGROUND
Chlamydia pneumoniae infection has been reported as a possible etiologic agent in asthma, which in primary care settings often appears to be initiated by acute respiratory infections.


OBJECTIVE
To determine if serologic markers for C. pneumoniae are associated with adult asthma that first became symptomatic after an acute respiratory illness (asthma associated with infection: AAWI).


METHODS
Serum samples from 164 primary care outpatients, mean age 44 years, (68 with AAWI; 36 with atopic, occupational or exercise-induced asthma (non-AAWI); 16 nonasthmatic patients with acute bronchitis; and 44 asymptomatic nonasthmatic controls) were tested for the presence of C. pneumoniae-specific IgG and IgA antibodies. Levels of chlamydial heat shock protein 60 (CHSP60) antibody were also measured. Those positive for CHSP60 were tested for C. pneumoniae-specific IgE antibodies by immunoblotting.


RESULTS
Statistically significant differences in IgG and IgA seroreactivity were noted between groups: acute bronchitis and AAWI had the highest levels (93% to 94% IgG seroreactivity, 69% to 75% IgA seroreactivity) whereas non-AAWI and asymptomatic controls had the lowest levels (61% to 84% IgG seroreactivity, 31% to 43% IgA seroreactivity, P < .02 after adjustment for age, sex and smoking). CHSP60 antibodies were significantly more prevalent in AAWI than in non-AAWI (19% versus 3%, P = .02). IgE antibodies against C. pneumoniae 60, 62, and/or 70 kD antigens were detected in 5 of 13 CHSP60 positive AAWI patients. Persistent IgG, IgA, and CHSP60 seroreactivities were noted in all seropositive asthma patients with serial serum samples.


CONCLUSIONS
Serologic markers of C. pneumoniae infection were associated with acute bronchitis and with asthma that first became symptomatic following respiratory illness. Serologic responses to C. pneumoniae may be useful in the classification and diagnosis of asthma.
Hahn
D L
DL
Dean Medical Center, Madison, Wisconsin, USA.
Peeling
R W
RW
Dillon
E
E
McDonald
R
R
Saikku
P
P
D000328:Adult; D000888:Antibodies, Anti-Idiotypic / Q000097:blood; D000907:Antibodies, Bacterial / Q000097:blood; D001249:Asthma / Q000097:blood* / Q000382:microbiology*; D015415:Biomarkers / Q000097:blood*; D001991:Bronchitis / Q000097:blood; D018834:Chaperonin 60 / Q000097:blood; D002690:Chlamydia Infections / Q000097:blood* / Q000175:diagnosis; D016993:Chlamydophila pneumoniae / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012698:Serologic Tests
D000888:Antibodies, Anti-Idiotypic; D000907:Antibodies, Bacterial; D015415:Biomarkers; D018834:Chaperonin 60; C049937:anti-IgA; C048844:anti-IgG