Fc epsilon RI, the high-affinity receptor for IgE, and eosinophils are thou
ght to be key components of the allergic reaction underlying asthma and rhi
nitis. We provide evidence at the protein level that FceRI is expressed in
human blood eosinophils, and that the synthesis of FceRI in purified human
blood eosinophils is regulated by fibronectin in combination with IgE, IL-4
, both involved in allergic reactions, and by RANTES, a strong chemotactic
agent for eosinophils. This provides further evidence for a regulatory effe
ct of IgE on human eosinophils in allergic disease.