Early and late allergic bronchial reactions: physiological characteristics

Abstract

Twenty-four patients with asthma of suspected allergic origin were subjected to a total of twenty-five bronchial provocations with the relevant allergen. Eighteen of them reacted with bronchial obstruction: eleven with an isolated early reaction, five with a dual reaction and two with only a late reaction. Extensive lung function tests were performed. The patterns of early and late reactions were qualitatively very similar regarding variables of pulmonary physiological function, but there were quantitative differences. Patients with dual reactions showed significantly greater changes in EEV|., RV and TGV during the early response than those with isolated early reactions. Maximum mid-expiratory flow rates with the patients breathing air and a mixture of He and O2 were measured before and 6 hr after the challenges. Four of five patients with both an immediate and a late response showed a decrease in the response to helium during the latter phase, suggesting increasing involvement ofthc smalt airways. An increase in the slope of the alveolar plateau (phase III) was observed in four of the five patients with dual responses and all five had increased CC%. It was concluded that the changes in pulmonary function occurring during the dual responses were widespread, involving the airways generally and resembling those in the clinically more severe asthma. Usually, individuals with dual reactions showed stronger reactions. In two cases, however, a late reaction was obtained without any preceding early reaction.

Small-airways dysfunction associates with respiratory symptoms and clinical features of asthma: A systematic review

“…Of interest, FEF 50% gradually decreased 6 and 24 hours after the allergen challenge, suggesting that the small airways contribute importantly to the late-phase asthmatic response. This is in agreement with the findings of Machado et al, 76 who similarly showed an immediate increase in FEF 50% after an allergen provocation, followed by a decrease in FEF 50% 6 hours later. Ahmed et al 77 studied the early asthmatic response to ragweed provocation, distinguishing reactors and nonreactors based on a 35% decrease in specific airway conductance.…”

“…74 The role of the small airways in the allergic response has been investigated by the change in the FEF 50% after breathing a mixture of helium-oxygen compared with room air. 75,76 Because of the lower gas density of helium, it can be assumed that a higher increase in FEF 50% will indicate obstruction in the more proximal airways, which are flow dependent. Metzger et al 75 studied the helium-oxygen flow-volume curves in 12 asthmatic patients with both an early-and late-phase allergic response based on a 20% and 10% decrease in FEV 1 , respectively.…”

Inhalation challenges with agents causing occupational asthma

“…It has been stated that isolated LARs are associated primarily with LMW agents, reflecting non-IgE-dependent mechanisms. However, isolated LARs have also been documented after SIC with HMW allergens [117,131,132], although such reactions seem to be rare. It is likely that the association between isolated LARs and LMW agents results from a methodological bias: during SIC the dose of HMW allergens is progressively increased until an immediate 20% fall in FEV1 is obtained, while exposure to LMW agents is usually increased on separate days.…”

Protective effects of deflazacort on allergen-specific conjunctival challenge

“…This early-phase reaction (EPR), similar to allergen provocation in the skin [11], lung [12,13] or nose [14], is characterized by clinical symptoms and local infiltration by inflammatory cells (mainly neutrophils) [8,15]. Bonini et al described a second clinical reaction, termed the late-phase reaction (LPR) following CPT, appearing i hour later, peaking at 6-8 hours after challenge, and slowly subsiding (over 24 hours or more).…”