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IgG subclasses in smokers with chronic bronchitis and recurrent exacerbations
I Qvarfordt1, G C Riise, B A Andersson
1Department of Respiratory Medicine and Allergology, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden. ingemar.qvarfordt@medfak.gu.se
Thorax
|May 22, 2001
Summary
Smoking lowers immunoglobulin G (IgG) levels, but this reduction does not explain recurrent infections in smokers with chronic bronchitis (CB). Smoking itself accounts for decreased IgG subclasses.
Area of Science:
- Immunology
- Pulmonology
- Tobacco Research
Background:
- Smokers exhibit lower serum immunoglobulin G (IgG) levels compared to non-smokers.
- IgG subclass deficiency is linked to recurrent respiratory infections, common in smokers with chronic bronchitis (CB).
Purpose of the Study:
- To investigate if altered IgG subclass levels or deficiency correlate with recurrent exacerbations in smokers with CB.
- To determine if smoking per se explains reduced IgG subclass levels in these patients.
Main Methods:
- Serum levels of IgG, IgA, IgM, and IgG subclasses 1-4 were measured using radial immunodiffusion in 100 subjects.
- Participants included smokers with stable CB and exacerbations, asymptomatic smokers, and healthy never-smokers.
- Serum cotinine ELISA confirmed systemic tobacco exposure, and data were log-transformed for statistical analysis.
Main Results:
- Both patients with CB and asymptomatic smokers showed significantly lower IgG and IgG2 levels than never-smokers.
- The reduction in IgG and IgG2 levels was comparable between smokers with CB and asymptomatic smokers.
- No significant differences in IgG subclass levels were found between the two smoking groups.
Conclusions:
- Recurrent exacerbations in smokers with CB are not associated with lower IgG subclass levels beyond what is explained by smoking.
- Smoking is the primary factor contributing to decreased IgG subclass levels in this population.