Abstract
The interleukin-5 (IL-5)-IL-5-receptor system has been of great interest because the IL-5-receptor (IL-5R) contains the common cytokine-receptor β-chain (βc), which is shared with the GM-CSF receptor and IL-3 receptor. IL-5 is produced by type 2 T helper cells (Th2), mast cells, and eosinophils, and non-hematopoietic cells. As we discuss, IL-5 has pleiotropic actions, from enhancing the homeostatic proliferation and survival of B-1 cells through noncognate stimulation and driving the differentiation of B-1 and B-2 cells into terminally differentiated plasma cells to augmenting the survival and activation of eosinophils. Thus, IL-5 links natural and adaptive immunity specific to the epitopes of natural ligands and exogenous antigens leading to the inducion of Ig-producing cells, regulating chronic inflammation and controlling disease. The potential roles of IL-5 in immune responses, allergy and autoimmunity make it attractive candidate for use in the clinical setting.
