Regulatory role of cytokines in IgE-mediated allergy

The discovery of immunoglobulin E (IgE) is considered the most important contribution, to date, in the field of clinical allergy. Studies in rodents and humans have suggested that IgE production could be regulated by antigen-specific helper and suppressor T cells and by isotype-specific factors having affinity for IgE. In recent years, the synthesis of IgE has been shown to be regulated, in part, by a cytokine network. This review summarizes the cytokines that up-regulate (interleukins-4, 5, and 6) and down-regulate (interferon-gamma and interleukin-2) the production of IgE. Emphasis is placed on IL-4 and IFN-gamma, two lymphokines known to play a major, but reciprocal, role in IgE synthesis. Increased insight into the various mechanisms of IgE control by cytokines and their receptors will eventually lead to improved treatment strategies in the clinical management of IgE-mediated allergy.