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The effect of tobacco smoke on immune function in twins

Institution: University of Southern California
Investigator(s): Wendy Cozen, D.O., M.P.H.
Award Cycle: 1998 (Cycle 7) Grant #: 7RT-0134H Award: $822,641
Subject Area: Epidemiology
Award Type: Research Project Awards

Initial Award Abstract
Environmental tobacco smoke is thought to be responsible for asthmatic episodes in millions of children each year. Children of mothers who smoke are 2-5 times more likely to be diagnosed with asthma than children of non-smoking mothers. It is not known how tobacco smoke causes asthma but an allergic pathway may be involved. Smoker have increased levels of a particular gamma globlulin, IgE. IgE is also elevated in people with allergies. IgE binds to special cells in the lining of the airways where it causes the cells to release powerful bronchoconstrictors. Cytokines are proteins that regulate the immune system and are produced by white blood cells. Two cytokines, IL-4 and IL- 13 control the production of IgE and are, therefore probably, involved in producing asthmatic reactions. A third cytokine, IL-5, controls the recruitment of the special immune cells that bind to IgE, eosinophils, into the lining of the airways, and may also be involved. One poorly designed study suggests that smokers have higher levels of LL-4 and IL-5 than non-smokers. The investigators did not evaluate other factors, such as race, age and sex, in the smokers and non-smokers which may have been responsible for the different levels. We propose to compare cytokine levels of IL-4, IL-5, IL-13 and IgE in healthy identical twin pairs, in whom one member smokes and the other does not smoke. In addition, we will compare cytokine and IgE levels in non-smoking twin pairs, in whom one member is exposed to passive smoke and the other is not. Since twins are naturally matched on genes, age, race and gender, we will be able to isolate the affects of smoking on the tobacco levels. Twins will be recruited from the California Twin Program. Smoking history information will be obtained from questionnaires previously completed and returned by the twins. Twins will obtain blood samples at their physicians' offices and mail them to us in pre-paid Federal Express mailers. Serum will then be sent to the California State Public Health Laboratories for IgE analysis. Cytokine levels will be analyzed here in our laboratories. If we observe an association between smoking and these immunological measures, it will increase the understanding of how tobacco smoke leads to asthma and allow us to design effective interventions.