The effects of theophylline on 661-1661-1661-1on polymorphonuclear leukocytes of asthmatic children and juveniles

Abstract

The density (B_max) and affinity (K_D) of β₂-adrenoceptors in polymorphonuclear leukocytes (PMN) were measured in 29 children and juveniles with mild or moderate asthma and in 25 healthy control subjects using the highly specific radioligand (±)-¹²⁵I-cyanopindolol. No significant difference in B_max was found between asthmatic subjects without medication and the control group. The asthmatic subjects were divided into four different groups by their actual medication: no medication, adrenergics, theophylline, adrenergics plus theophylline. Analysis of variance revealed highly significant differences between these groups for B_max (P=0.0016) but not for K_D. In asthmatics on adrenergic therapy B_max was significantly lower (995±415) than in asthmatics without medication (1660±521;P=0.008). In contrast, B_max in asthmatics on theophylline therapy was significantly higher (2137±231;P=0.009) than in the controls. B_max was average in the group of asthmatics treated with both adrenergics and theophylline (1619±547). It is concluded that in asthmatic subjects therapy with theophylline increases the density of β₂-adrenoceptors and partly prevents their down-regulation induced by adrenergic therapy.