An epidemiologic study of the interrelationships of total serum immunoglobulin E,allergy skin-test reactivity,and eosinophilia

In a general population sample from Tucson, Arizona, we examined the effects of age, sex, and smoking habits on the interrelationships of total serum IgE, allergy skin-test reactivity, and peripheral blood eosinophilia. Allergy skin-test reactivity showed a direct linear relationship to total serum IgE, but this relationship was differentially affected by age and smoking habits. The frequency of positive skin-test reactivity for a given level of IgE was greater among females than that among males, but a comparison of female and male nonsmokers indicated that this difference was attributable to differences in smoking habits rather than sex. Subjects less than 16 and those over 45 yr of age demonstrated reduced skin-test reactivity for a given level of IgE when compared with subjects 16 to 45 yr of age. Restricting the analysis to nonsmokers diminished (but did not obliterate) this age effect. Those over 45 yr of age (but not those less than 16) were shown to have reduced levels of IgE specific for Bermuda grass as compared with the 16 to 45 yr age group. The skin of subjects less than 16 and those over 65 yr of age was reduced in its capacity to respond to histamine. Thus the reduction in the skin-test reactivity of subjects less than 16 yr of age appears to involve a reduction in their skin reactivity to mediators, whereas for those over 45 it is related to a reduction in IgE specific for common aeroallergens, and for those over 65 it is apparently related to both of these causes. The frequency of peripheral blood eosinophilia was also found to be directly related to total serum IgE. Skin test-negative subjects had the same frequency of eosinophilia as that in skin test-positive subjects at any given level of serum IgE. Males had higher rates of eosinophilia than did females for a given level of IgE, but this difference also became insignificant if the analysis was restricted to nonsmokers. The increase in eosinophilia among smokers as compared with nonsmokers with equivalent serum IgE levels implies that smoking may trigger immunologic reactions associated with eosinophilia.