SERUM HOUSE-DUST MITE ANTIBODIES - PREDICTOR OF INCREASED BRONCHIAL RESPONSIVENESS IN ADULTS OF A COMMUNITY

The purpose of this study was to determine whether the presence of ser um specific immunoglobulin E (IgE) antibodies was associated with incr eased bronchial responsiveness in adults. We studied cross-sectionally a random community sample of 18-73 year old adults, of whom 83 % (n=4 89) performed bronchial responsiveness testing as well as serum measur ements of five specific IgE antibodies. In the crude data, 39% of thos e with house dust mite antibodies (n=18) had a bronchial responsivenes s less than or equal to 32 g . L(-1) methacholine compared with 19% in subjects without any of the five specific IgE antibodies (n=453). The corresponding percentages for subjects with timothy antibodies (n=16) was 25%, birch antibodies (n=13) 23%, cat antibodies (n=10) 40% and m ould antibodies (n=2) 50%. When assessing the multivariate relationshi p between the presence of one specific IgE antibody and degree of bron chial responsiveness we used a semi-proportional hazards model with th e response as a 20% fall in forced expiratory volume in one second (FE V(1)) from pretest value. Covariates included in the model were: gende r, age, pretest FEV(1), smoking habits, pack-years, season and other s pecific IgE antibodies than that examined. The presence of house dust mite antibodies was a significant predictor (p<0.01) of increased bron chial responsiveness in never- and ex-smokers, Indoor allergic sensiti zation (house dust mite, cat and mould) was a significant predictor of increased bronchial responsiveness, while outdoor allergic sensitizat ion (timothy and birch) was not. Excluding subjects with obstructive l ung disease (n=39) or including the covariate log total serum IgE as a potential confounder yielded the same result. Thus, in this community , indoor allergic sensitization rather than allergic sensitization per se was related to increased bronchial responsiveness after adjusting for other relevant covariates.