Table 1 summarizes the activities of hemopoietins on immature and mature basophils. IL-3, GM-CSF, and IL-5 enhanced basophil histamine release and in-vitro survival, while G-CSF, M-CSF, and IL-4 had no enhancing activities at all. In addition, IL-3 and GM-CSF induced basophil chemotaxis. Although IL-3 was proved to have proliferative and differentiation-inducing activities on basophils in vitro and in vivo, the other two factors (GM-CSF and IL-5), which are also capable of regulating basophil functions and viability, might potentially participate in proliferation or differentiation of human basophils, but this hypothesis remains without sure foundation. Studies on the roles of both factors in human basophilopoiesis need extension. The fact that IL-3, GM-CSF, and IL-5 regulate basophil function and viability in vitro demonstrates possible mechanisms for the regulation of basophil function and viability in IgE-mediated reactions (especially in late-phase reactions) in vivo by these factors. Since these factors could be produced by antigen-stimulated T-cells or epithelial cells through the inflammatory process, these factors could participate in exacerbation and prolongation of hypersensitivity reactions by inducing the migration and enhancing functions and the lifespan of basophils.