An increase in bronchial hyperresponsiveness by cigarette smoking in elderly patients with asthma

Influence of cigarette smoking on the pathogenesis of asthma in the elderly remains controversial. This study was undertaken to clarify the influence of cigarette smoking on IgE-mediated allergy, bronchial hyperresponsiveness, and the generation of leukotrienes B4 (LTB4) and C4 (LTC4) by leukocytes in 48 elderly patients (25 patients with a history of smoking for more than 20 years and 23 never-smokers) with asthma over the age of 70 years. 1. The incidence of positive IgE antibodies for inhalant allergens was significantly higher in asthmatics with a history of smoking than in never-smokers of asthmatics. 2. In bronchial hyperresponsiveness for methacholine, the Cmin was significantly lower in ever-smokers than in never-smokers of elderly asthmatics. 3. The generation of LB4 was significantly increased in patients with a history of smoking compared with those without a smoking history. However, the difference in LTC4 generation was not significant between ever-smokers and never-smokers of asthmatics. These results suggest that cigarette smoking increases bronchial hyperresponsiceness through IgE-mediated allergy and LTB4 generation.

高齢者喘息の病態におよぽす喫煙の影響についてはなお不明な点が多い｡本論文では,IgEにmediateされるアレルギー反応,気道過敏性,ロイコトリエンB4 (LTB4),C4(LTC4)産生に及ぼす喫煙の影響について,48例(20年以上の喫煙歴のある症例25例,非喫煙例23例)の70歳以上の高齢者喘息症例を対象に検討した｡ 1.吸入抗原に対する特異的IgE抗体の陽性頻度は,喫煙歴のある症例で,非喫煙例と比べ有意に高い値を示した｡ 2.メサコリンに対する気道過敏性の検討では,平均Cminは,喫煙例(949μg/ml)において非喫煙例(1677μg/ml)に比べ有意に低い値 を示し,喫煙例でより気道の過敏性が高いことが示された｡ 3.LTB4の産生は喫煙例で非喫煙例に比べ有意に高い傾向を示したが,LTC4に関しては両群間に有意の差は見られなかった｡以上の 結果より,長期間の喫煙は,IgEにmediateされるアレルギーやLTB4産生の亢進などを通じて気道過敏性を亢進させる可能性が示唆された｡