THE IMMEDIATE AND LATE ALLERGIC RESPONSE TO SEGMENTAL BRONCHOPULMONARY PROVOCATION IN ASTHMA

The response to antigen is an important factor in the development of a irway inflammation. Segmental bronchoprovocation (SEP) with antigen an d subsequent bronchoalveolar lavage (BAL) have provided valuable insig ht into the mechanisms of allergic inflammation. To determine the feat ures of allergic airway response in asthma, 19 subjects with mild asth ma underwent antigen SEP in a dose-dependent manner. The amount of ant igen used in SEP was 0 (saline), and 1, 5, or 20% of the antigen dose required to drop the FEV1 by 20% (APD(20)). BAL was done at 5 min and 48 h after SEP. BAL histamine levels increased modestly 5 min after an tigen SEP. At 48 h, there was a marked increase in eosinophils and IL- 5 concentration even in airway segments where the release of histamine was smart. Moreover, eosinophils correlated with IL-5 levels at 48 h (r = 0.63; p < 0.001), but not with BAL histamine concentrations at 5 min. CM-CSF levels did not increase after antigen SEP and did not corr elate with eosinophils. These observations indicate that asthmatic sub jects can develop a dose-dependent response to antigen SEP that is cha racterized by a modest increase in histamine immediately after antigen exposure, and marked eosinophilia, which appears proportionately grea ter than the histamine response and relatively greater than what is se en in allergic nonasthmatic subjects. This feature might be important to the eventual development of airway inflammation in asthma.