The identification and characterization of umbilical cord blood-derived human basophils

Cross-linking allergen-specific immunoglobin E on human peripheral blood basophils results in the release of histamine and other inflammatory mediators that initiate allergy and asthma. The signaling pathways leading from IgE binding to mediator release have not been well established, mainly due to the difficulty in obtaining adequate numbers of highly purified basophils, It was the goal of this study to easily obtain Fc epsilon RI-positive human basoplrils in high yield and purity for studies of signal transduction pathways, We describe all in vitro culture system in which pulsing normal human cord blood leukocytes with interleukin-3 (IL-3) for 3-4 h followed by incubation in medium with fetal bovine serum generates a cell population that is predominately Fc epsilon RI positive between 14 and 28 days of culture. These cells resemble peripheral blood basophils when examined by light and electron microscopy. Like normal blood basophils, they express the integrins, CD11b, CD18, CD29, and CD49d. A majority of the IL-3-pulsed cells also express a marker recognized by the basophil-specific antibody, 2D7, Fc epsilon RI cross-linking results in a time and dose-dependent release of histamine. Fc epsilon RI cross-linking also stimulates protein-tyrosine phosphorylation, thought to be the first event leading to the IgE-mediated activation of peripheral blood basophils, These studies establish cord blood as an accessible source from which basophil-like cells call be developed to examine Fc epsilon RI-mediated signal transduction.