Smoking inhibits the increase in non-specific reactivity following challenge

There is controvosy regarding the frequency of normal measurements of non-specific reactivity (nsbr) in currently exposed workers with occupational asthma. A possible explanation comes from the unexpected finding that the increase in non-specific reactivity  seen after a late asthmatic reaction was absent in mild asthmatics who smoked but present in the non-smokers as expected. A hypothesis presented was that increased CO in smokers may inhibit cGMP in bronchial muscles (as found in mice). However exhaled CO was not measured in this study. Although the challenges in this study were with environmental allergens (mainly ragweed and cat)the finding may account for the lack of nsbr found in about 30% of workers with occupational asthma

References

	Meghji Z, Dua B, Watson RM, Gauvreau GM, OByrne PM, Allergen inhalation challenge in smoking compared with non-smoking asthmatic subjects, Clin Exp Allergy, 2011;41:1084-1090,

	Beach J, Russell K, Blitz S, Hooton N, Spooner C, Lemiere C, Tarlo SM, Rowe BH, A Systematic Review of the Diagnosis of Occupational Asthma, Chest, 2007;131:569-578,

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