Recruitment/replenishment

A transient decrease in eosinophils in the circulation 2 hours before the LAR has been described (Cookson et al., 1989), and this is followed within 24 hours by an increase in circulating eosinophils, a greater proportion of which have the activated hypodense phenotype (Calhoun et al., 1991) and express surface activation markers. At the same time, increased eosinophil numbers are observed in BAL fluid (De Monchy et al., 1985) and in bronchial mucosal biopsies (Frew et al., 1995). These results suggest that following allergen challenge eosinophils are selectively recruited into the lung from the vasculature, and replenished by an increased proliferation or release of eosinophils in the bone marrow. 

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