Relationship between types of asthmatic reaction, nonspecific bronchial reactivity, and specific IgE antibodies in patients with red cedar asthma. 
We studied the relationship between specific IgE antibodies, nonspecific bronchial reactivity to methacholine, and the type of asthmatic reaction in patients with red cedar asthma.  The level of circulating specific IgE antibodies (expressed as RAST ratios) was not related to the type of asthmatic reaction, the degree of nonspecific bronchial hyperreactivity [expressed by the provocative concentration of methacholine producing a 20% decrease in the forced expiratory volume in 1 sec (PC20)] or the index of reactivity to plicatic acid.  On the other hand, methacholine PC20 was found to correlate with the index of reactivity to plicatic acid in the late asthmatic reaction (LAR) and both the immediate and late components of the dual asthmatic reaction (DAR).  Development of the LAR is associated with increase in nonspecific bronchial hyperreactivity.  Repeated inhalation challenge with plicatic acid in eight patients with LAR resulted in DAR in all.  The results suggest that the mechanism responsible for the LAR is associated with an increase in nonspecific bronchial reactivity; furthermore, the immediate component of DAR could also be related to heightened bronchial hyperreactivity.