IGE REGULATES MOUSE BASOPHIL FC-EPSILON-RI EXPRESSION IN-VIVO

The binding of IgE to high-affinity IgE receptors (Fc epsilon RI) on t he surface of mast cells and basophils primes these cells to secrete a panel of proinflammatory mediators upon subsequent exposure to specif ic Ag. We now find that the level of Fc epsilon RI expression on bone marrow basophils in mice infected with the nematode Strongyloides vene zuelensis exhibits a strong positive correlation with the serum concen tration of IgE, as was previously reported for human blood basophils. Moreover, the administration of IgE in vivo can significantly up-regul ate Fc epsilon RI expression on mouse basophils, and genetically IgE-d eficient (IgE -/-) mice exhibit a dramatic (similar to 81%) reduction of basophil Fc epsilon RI expression compared with the corresponding n ormal (IgE +/+) mice. The finding that IgE can be a major regulator of mouse basophil Fc epsilon RI expression in vivo identifies a potentia lly important mechanism for enhancing the expression of effector cell function in IgE-dependent allergic reactions or immunologic responses to parasites.