The relationship between development of lung inflammation and changes in bone marrow populations in guinea-pigs following inhaled antigen challenge.

Sensitised guinea-pigs were exposed to aerosolised antigen. The resultant cellular infiltration into the lung was assessed in lung tissue and bronchoalveolar lavage fluid 6, 24, 72 h and 7 days later. An early neutrophil infiltration peaking at 6 h was succeeded by eosinophil migration which persisted for 7 days, at which time some of the eosinophils appeared immature. The lung eosinophilia was accompanied by an initial fall in eosinophilic cells in the bone marrow, followed by an increase in this population. Treatment with dexamethasone (25 mg/kg i.p.) given daily for 7 days after antigen challenge reduced the lung eosinophilia and observed bone marrow changes.