Eosinophil chemotactic activity in allergic patients during the birch pollen season: the effect of immunotherapy.

Recently, heat-labile eosinophil chemotactic activity (ECA) has been found in serum after challenge of allergic asthmatic patients. In this study, we investigated changes in ECA in 40 birch-allergic patients during the birch pollen season; 20 of them had been treated with immunotherapy of birch pollen extract before the season. ECA raised significantly (p less than 0.001) in the untreated birch pollen-allergic patients during the season. Immunotherapy completely abolished this activity.