Quantification of the dose of inhaled flour: relation with nonspecific bronchial and immunological reactivities

Abstract

Because both bradykinin and tachykinins have a potent inflammatory action, these molecules may be involved in the late allergic response. The role of these molecules in airway microvascular permeability during the late allergic response in sensitized guinea-pigs was investigated.Three weeks after ovalbumin sensitization, the animals were pretreated with bradykinin B 2 receptor antagonist HOE 140, neurokinin 1 receptor antagonist CP 96,345 or vehicle, 30 min before the ovalbumin inhalation challenge. The occurrence of the late allergic response was determined by a two-fold increase in the transpulmonary pressure from the baseline values. The microvascular permeability in the trachea was assessed by an index defined as the ratio of the area of vasculature labelled by Monastral blue dye (area density %).Significant microvascular permeability and eosinophil accumulation were observed during the late allergic response. Both the bradykinin and substance P concentrations in the bronchoalveolar lavage fluid were increased during the late allergic response. Pretreatment with HOE 140 suppressed the substance P elevation. Both HOE 140 and CP 96,345 also inhibited the airway microvascular permeability during the late allergic response without affecting the eosinophil accumulation in the airways.These findings suggest that bradykinin-mediated sensory nerve activation may play a role in microvascular permeability during the late allergic response in guinea-pigs.

Bronchial challenge with flour: early response is dependent on the dose of activated allergen inhaled

“…Sometimes the ambient concentration is measured, but inhaled dose is seldom determined. The way to express results and the criteria of positivity are not as well defined as for the methacholine test [1][2][3][4]. However, a 20% (or 15%) fall in forced expiratory volume in one second (FEV1) is the criterion usually used to indicate a positive early reaction [1,[3][4][5].…”

“…The way to express results and the criteria of positivity are not as well defined as for the methacholine test [1][2][3][4]. However, a 20% (or 15%) fall in forced expiratory volume in one second (FEV1) is the criterion usually used to indicate a positive early reaction [1,[3][4][5]. The current authors have demonstrated that the fall in FEV1 during the specific challenge can be compared to the distribution of the values of FEV1 during the control test with lactose [3].…”

“…However, a 20% (or 15%) fall in forced expiratory volume in one second (FEV1) is the criterion usually used to indicate a positive early reaction [1,[3][4][5]. The current authors have demonstrated that the fall in FEV1 during the specific challenge can be compared to the distribution of the values of FEV1 during the control test with lactose [3]. If the inhaled dose is measured, the specific reactivity can be expressed as the provocative dose of flour causing a 20% or 15% fall in FEV1 (PD f 20 or PD f 15, respectively).…”

“…If the inhaled dose is measured, the specific reactivity can be expressed as the provocative dose of flour causing a 20% or 15% fall in FEV1 (PD f 20 or PD f 15, respectively). Several studies of various allergens have shown that the range of specific reactivity among asthmatic subjects is wide [3,[6][7][8][9].…”

“…The test is short when the FEV1 falls after the first inhalation of allergen, but in some cases the test can last several hours before a decrease in FEV1 is observed [1,3]. VANDENPLAS et al [7] have demonstrated that the main determinant of bronchial responsiveness to isocyanates, among subjects with a change in FEV1w20%, is the total inhaled dose and not concentration nor duration of exposure per se.…”