Inflammation and the late phase reaction in asthma: the effect of polymorphonuclear leukocyte depletion on airways obstruction and bronchial hyperreactivity in an animal model.

Increases in airway reactivity noted after antigen exposure in which a late asthmatic response (LAR) develops may be related to pulmonary inflammation. Employing an animal model of the LAR developed in our laboratory, we conducted experiments to determine if depletion of polymorphonuclear leukocytes (PMLs) would ablate the LAR and inhibit subsequent increases in airways reactivity. Four groups of ten animals each were studied. The first group was given immune sera (I) containing anti-ragweed IgE. The second group received non-immune sera (NI). A third group of animals received immune sera plus nitrogen mustard (I + NM), while a fourth group received non-immune sera plus nitrogen mustard (NI + NM). Airways reactivity to histamine and the evaluation of different cell types in bronchoalveolar lavage fluid (BALF) were determined three days before and three days after bronchial challenge with ragweed extract (RWE). No control rabbit (NI or NI + NM) developed either an immediate asthmatic response (IAR) or an LAR, and no significant increases occurred in their airways reactivity or cells in lavage fluid after bronchial challenge with RWE. In contrast, the sensitised rabbits not given nitrogen mustard developed an LAR and airways reactivity increased markedly three days later. Those animals receiving immune sera and nitrogen mustard developed an IAR; however, no LAR occurred and no significant change in airways reactivity ws observed. BALF analysis seventy-two hours after ragweed challenge in the animals that received immune sera showed a significant increase in PMLs. However, there was no significant increase on BALF PMLs in the animals receiving immune sera and nitrogen mustard.(ABSTRACT TRUNCATED AT 250 WORDS)