Effects of asthma on cell components in peripheral blood among smokers and non-smokers

Authors

  • J. Sunyer,

    1. Institut Municipal Investigació Mèdica (IMIM) and Universitat Pompeu Fabra, Barcelona, Catalonia, Spain,
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  • G. Springer,

    1. Department of Epidemiology and Department of Molecular Microbiology and Immunology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA,
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  • B. Jamieson,

    1. Department of Medicine, University of California at Los Angeles School of Medicine, CA, USA,
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  • C. Conover,

    1. CORE Center, Cook County Hospital, Chicago, IL, USA,
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  • R. Detels,

    1. Department of Epidemiology, University of California at Los Angeles School of Public Health, Los Angeles, CA, USA, and
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  • C. Rinaldo,

    1. Department of Microbiology and Infectious Diseases, Department of Pathology, University of Pittsburgh School of Public Health, Pittsburgh, PA, USA
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  • J. Margolick,

    1. Department of Epidemiology and Department of Molecular Microbiology and Immunology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA,
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  • A. Muñoz

    1. Institut Municipal Investigació Mèdica (IMIM) and Universitat Pompeu Fabra, Barcelona, Catalonia, Spain,
    2. Department of Epidemiology and Department of Molecular Microbiology and Immunology, The Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD, USA,
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Alvaro Muñoz, Ph.D., Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Suite E-7008, Baltimore, MD 21205-2179. E-mail: amunoz@jhsph.edu

Summary

Background  Eosinophils play a central role in asthma, but the interplay of the effects of smoking, eosinophils and asthma remains unclear.

Objective  The primary objective of our study was to investigate the extent to which smoking modifies the effect of asthma on circulating eosinophils, CD4+ and CD8+ T cell counts.

Methods  Data were collected semiannually between 1987 and 1994 from HIV-negative participants in the Multicenter AIDS Cohort Study. Asthma was defined by a questionnaire at baseline as a self-report of diagnosed asthma. A total of 1420 blood samples from 197 asthmatics and 15 822 from 1997 non-asthmatics were collected.

Results  Eosinophil levels were higher in asthmatics (28% of asthmatics had eosinophils geqslant R: gt-or-equal, slanted4% and 16% of non-asthmatics) regardless of smoking history, but smoking modified the association between eosinophils and asthma. Namely, the odds ratios for eosinophils being geqslant R: gt-or-equal, slanted4% in asthmatics to non-asthmatics decreased from 2.7 (95% CI: 2.0, 3.6) in never, to 2.1 (1.4, 3.1) in former, and to 1.5 (0.9, 2.3) in current smokers. Cross-sectional and longitudinal analyses coherently showed that smoking increased eosinophils in non-asthmatics, but the converse was true for asthmatics. In contrast, no differences in peripheral blood T cell counts between asthmatics and non-asthmatics were observed.

Conclusion  Under the established link between increased eosinophils and asthma, these data indicate that smoking modified this relationship. This finding suggests that smoking plays a different immunological role in asthmatics and non-asthmatics.

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