Control (nonragweed-immune) rabbits had neither immediate nor late responses after exposure to this antigen, while ragweed-immune rabbits had early and late decreases in lung function. In addition, marked increases in airway reactivity to histamine were noted in the ragweed-immune group. These observations suggest that the granulocytic series of cells is important in the production of […]

Importance of Inflammatory Cells In LAR Late phase reactions in man and animal models have been associated with inflammation within the involved tissue. In terms of LAR, bronchoalveolar lavages performed after antigen challenges that led to LARs have shown accumulations of inflammatory cells. For example, de Monchy et al found the LAR was associated with […]

Factors That Determine LAR Several factors are probably important in determining whether an allergic reaction subsides after an immediate response or progresses to a late phase reaction. One modulating factor is the level of antigen-specific IgE within the host; higher levels of IgE have generally correlated with the development of LARs. Conversely, antigen-specific IgG may […]

Thus, within the skin of man, the evidence is strong that late responses to antigen can be dependent on IgE. The hypothesis that late phase reactions within the airways may also depend on IgE is more difficult to study in man. A recent report by Kirby et al did find that inhalation of sheep anti-human […]

Late stimulus and for many reasons is thought to resemble more closely the problems for which patients seek assistance than the immediate asthmatic response (IAR) that occurs within minutes of challenge. For example, the airway obstruction produced during LAR may be more severe and prolonged than that associated with IAR. In addition, the IAR may […]

Contractile actions of histamine are mediated directly via stimulation of Hx-histamine receptors on airway smooth muscle and, in part, indirectly via stimulation of vagal reflex causing release of acetylcholine at the parasympathetic nerve endings. Inhibition of histamine-induced bronchoconstriction by the anticholinergic agent, ipratropium bromide, in our normal subjects is consistent with this concept. Thus, it […]

Our results demonstrate differences between normal and asthmatic subjects in terms of agonist-agonist interaction. Whereas in normal subjects prior muscarinic stimulation suppressed the histamine-induced bronchoconstriction, no such suppression was observed in subjects with asthma. It is possible that lack of suppressive action of methacholine on histamine-induced bronchoconstriction in asthmatic subjects may be related to two […]

Our in vivo results are consistent with the in vitro findings of Ishii and Kato10 who observed suppression of histamine-induced contraction of guinea pig ileum by prior exposure of the tissues to methacholine. They also observed that the suppressive action of methacholine on subsequent histamine-induced contraction was specific, as neither methacholine nor histamine exposure had […]

Effect of Prior Muscarinic Receptor Stimulation on Histamine and Methacholine-induced Bronchoconstriction In the normal group, prior muscarinic receptor stimulation with methacholine caused a rightward shift in the histamine dose-response curve in most of the subjects and a significant increase in histamine PD.50 (Fig 1 and 2). The mean ± SE histamine PD^ on a control […]

Experimental Protocol Each subject was studied on five occasions separated by at least 72 h. On experiment day 1, after obtaining baseline pulmonary (unction test results, a control bronchial provocation test with histamine was performed to establish PD*, to histamine. Normal subjects in whom PDg„ was not achieved even with 5 mg/ml concentration of histamine […]