Comparative study of two methods for spinhaler-specific bronchoprovocation challenges. II.

Two different methods of performing specific bronchial challenge using a micronized freeze-dried extract of D. pteronyssinus administered as a powder by a spinhaler have been evaluated in 11 children with chronic asthma and skin test RAST positive for house dust mite D. pteronyssinus. In the first method, "Cumulative Dose Method" (CDM), the test doses of antigen [0, 50, 100, 200, 400, 600, 800, and 1,000 Allergenic Units (A.U.)] were successively administered in 30-minute intervals. With the other method, "Daily Increasing Dose Method" (DIDM), a single antigen challenge (only one cup) was performed every day successively. The tests were considered positive when FEV1 values dropped below 20% of the value obtained immediately before the inhalation of the antigen. The early FEV1 fall was 36.6% +/- 10.8% with CDM and 29.1% +/- 11.5% with DIDM. There was a mean late fall of FEV1 52% +/- 17% and 35.3% +/- 12.2%, respectively, after a mean antigen administration of 270 +/- 149 A.U. with CDM and of 290 +/- 202 A.U. with DIDM. An increase in non-specific bronchial reactivity was observed after specific challenge performed with both methods. The CDM offers the advantage of obtaining information more quickly. The DIDM offers the advantage of administering a lower daily dose of antigen. Our results indicate that a modification of CDM with a shorter interval of administration may further improve this method of antigen administration.