Description
Interleukin-4 is produced mainly by a subpopulation of activated T-cells (Th2) which are the biologically most active helper cells for B-cells and which also secrete IL-5 and IL6. The biological activities of IL-4 are mediated by a specific receptor The extracellular domain of the IL4 receptor is related to the receptors for EPO, IL6, and the beta chain of the IL2 receptor. It has been given the name CD124. Two types of IL4 receptor (IL4R) exist: the type 1 receptor is a heterodimer consisting of CD132 and IL4R-alpha. The type 2 receptor is a heterodimer consisting of IL4R-alpha and IL13R-alpha- 1. IL4 enhances expression of MHC class 2 antigens on B- cells. It can promote their capacity to respond to other B-cell stimuli and to present antigens for T- cells.Pretreatment of macrophages with IL4 prevents the production of IL1, TNF-alpha and prostaglandins in response to activation of the cells by bacterial endotoxins or IFN-gamma