Adenosine deaminase and lymphocytic populations.

regard, the recent article by Yellowlees and Kalucy (Chest 1990; 97:628-34) and the accompanying editorial by Gorman (Chest 1990; 97:514-15) were of great interest. With respect to the apparent efficacy of anti-depressant medications in asthmatic patients, however, it is important to consider the antihistaminic properties (which are not widely appreciated) that these agents possess. Tricyclic antidepressant drugs are extraordinarily potent H and H2 antihistamines. Doxepin is approximately 775-fold more potent an H1 inhibitor than diphenhydramine on a molar basis.’ Anxiolytic properties of commonly used H1 antihistamines are well known. Antihistamines given to asthmatic patients can promote dose-related bronchodilation and attenuate immediate bronchospastic responses to inhaled allergen and exercise.24 An increasing therapeutic role for H1 antihistamines in asthma has been suggested with recent availability of agents that are nonsedating and lack significant anticholinergic effects. It is important for both asthma and psychiatry/psychology subspecialists to be aware of the dual actions of antidepressant! antihistamine drugs-potentially effective in altering mood and also