[Influence of theophylline and corticosteroid preparations on serum PAF acetylhydrolase activity in asthmatic children].

In our previous papers, we reported that serum PAF acetylhydrolase (PAF AH) activity in severely asthmatic children was lower than that in healthy or mildly asthmatic children, and that this enzymatic activity might be one of the factors that induce more severe respiratory symptoms in asthmatic children. In this study, we investigated the influence on PAF AH activity of theophylline and corticosteroid preparations, which are frequently used for the treatment of patients with bronchial asthma. Serum PAF AH activity and theophylline concentration were measured before and 3,4,6, 12 h after administration of a sustained-release theophylline preparation to 8 asthmatic children. Although the theophylline concentration was increased significantly at 3, 4 and 6 h after administration, PAF AH activity was unchanged, and there was no correlation between the two parameters. We then measured PAF AH activity in 6 asthmatic children before and 5 and 48 h after intravenous injection of 100 mg hydrocortisone succinate, and found no change in enzymatic activity. Furthermore, PAF AH activity in two severely asthmatic patients, who were being given low-dose corticosteroid on alternate days, was measured at regular intervals for 10 months in one case and 5 months in the other. The PAF AH activity showed no significant change in this period. These results show that PAF AH in asthmatic children is very stable, and is not affected by either theophylline or corticosteroid preparations.