Effects of aging on the pathophysiology of asthma obsetved by IgE-mediated allergy, pulmoanry function, low attenuation area of the lungs on HRCT, and LTB4, LTC4 generation

The influence of aging on the pathophysiology of asthma in the elderly was examined in 40 patients (20 younger asthmatics under the age of 50 years, mean age 32.5 years and 20 elderly asthmatics over the age of 70 years, mean age 74.3 years), relating to IgE - mediated allergy, pulmonary function, low attenuation area (LAA) of the lungs on HRCT, and the generation of leukotrienes B4 (LTB4) and C4 (LTC4) by leukocytes. The frequency of patients with serum IgE of more than 200 IU/ml, and the incidence of those with a positive RAST score for inhalant allergens were significantly higher in younger patients than in elderly subjects. The values of % FVC, % FEV1 and FEV 1% were significantly larger in younger patients compared with elderly subjects. The % RV was significantly larger in elderly patients than in younger patients, however, the difference in % DLco was not significant between the two age groups. The LAA of the lungs on HRCT and the ratio of expiratory LAA (exp LAA) to inspiratory LAA (ins LAA) were also significantly larger in elderly asthmatics than in younger subjects. The generation of LTB4 and LTC4 was larger in younger patients than in elderly subjects, and LTB4 generation was significantly larger in younger subjects compared with elderly subjects. These results suggest that changes in IgE-mediated allergy, airflow and lung volume accompanied with hyperinflation are often observed in elderly asthmatics.

70歳以上の気管支喘息20例(平均年令74.3歳)および50歳以下の気管支喘息20例(32.5歳)を対象に,IgEにmediateされるアレルギー反応,肺機能,HRCT上の肺のLAAの程度,白血球によるLTB4,LTC4産生などに対する加齢の影響について検討した｡血清IgE値が200IU/ml以上の症例の頻度および吸入抗原に対するRAST scoreが陽性を示す症例の頻度は,いずれも若青年者喘息で高齢者喘息と比べ有意に高い傾向を示した｡ % FVC,% FEV(1),FEV(1) % 値はいずれも若青年者喘息で高 齢者喘息に比べ有意に高い値を示し,また,% RVは高齢者で有意に高い値が示された｡一方,% DLcoは両者間に有意の差は見られなかった｡ HRCT上の% LAAおよびLAA比(呼気/吸気)いずれも高齢者喘息で有意に高い値を示し,加齢により肺のLAAが明らかに影響を受けることが判明した｡LTC4の産生は若青年者喘息でやや高い値が示されたが,高齢者との間に有意差は見られなかった｡一方,LTB4産生は,若青年者喘息で高齢者喘息と比べ有意に高い値が示された｡これらの結果は,70歳以上の高齢者喘息では加齢による影響を広範囲にわたり受けている可能性が高いことを示している｡