Immunoallergological studies were carried out to clarify the differenc
es between 24 patients with drug-induced asthma (DIA) and 240 with non
-drug-induced asthma (non-DIA). The mean values of age, skin reaction
to Candida albicans (C. albicans), serum IgE levels, specific IgE anti
bodies to house dust (IID) and C. albicans, bronchial sensitivity and
leukotriene B-4 (LTB(4)) synthesis from peripheral venous blood in pat
ients with DIA were not significantly different from those in patients
with non-DIA. In contrast, the frequency of positive skin reaction to
HD and histamine release from peripheral basophils by anti-IgE were s
ignificantly lower in DIA than in non-DIA. These results agree with th
e reports that DIA was often observed in non-atopic asthma. But, the m
ean value of serum IgE was very high in DIA as well as in non-DIA. Thi
s result suggests that IgE mediated reaction in DIA is important. Furt
hermore, the proportion of neutrophils in bronchoalveolar lavage fluid
(BALF) was significantly lower in DIA than in non-DIA. Our findings s
uggest that. a decrease of intrapulmonary neutrophils might play an im
portant role in the pathophysiology of DIA.