Influence of age on IgE responsiveness to Dermatophagoides farinae: an immunoblot study

IgE responsiveness to Dermatophagoides farinae body extract was compared by immunoblotting among four groups of mite-sensitive asthmatic children: group I aged 0-3, group II aged 4-7, group III aged 8-11 and group IV aged 12-15. In the group I subjects, the 15-kD component was bound by 88% of sera and strongly by 56% of sera. The 25-kD component was bound by 40% of sera, but most of the binding reactions were faint. IgE binding to other components was generally low. In the group II subjects, 15- and 25-kD components were bound by 96% and 56% of sera, 30-kD and 110-kD components by 76% and 60% of sera, respectively. In addition, 18-, 40-, 59- and 80-kD components were bound by more than 30% of sera. In group III and IV subjects, the frequencies of IgE binding to these components were not significantly changed as compared with those of group II subjects. The rabbit antisera against Der f I and Der f II specifically reacted with 25- and 15-kD components, respectively. These results suggest that the 15-kD Der f II allergen is the most important antigenic constituent associated with the early IgE response to house dust-mites in mite-reactive asthmatic children.