Cell-mediated immunity was examined in 45 patients with bronchial asthma by observing the delayed cutaneous reaction to purified protein derivative (PPD) and Candida albicans (C. albicans). The delayed skin reaction to PPD showed a decrease with age starting between 50 and 59 years old. The delayed reaction to PPD decreased more prominently with aging, being significantly depressed in the patients aged over 70 years than in those aged between 30 and 49 years (induration, p < 0.02; flare, p < 0.01). The C. albicans-induced skin reaction was significantly lower in the patients aged over 70 years than in those between 60 and 69 years old (induration, p < 0.01; flare, p < 0.05). The delayed skin reaction to PPD and C. albicans was significantly depressed in the patients with a serum IgE level over 1001 IU/ml. Delayed skin reaction to PPD and C. albicans was more depressed with aging and an elevated serum IgE, and the age (50-59 years) at the initiation of depression in the PPD-induced delayed skin reaction was younger than that (over 70 years) in the C. albicans-induced reaction.</p
