Interleukin 4 (IL-4) is a pleiotropic cytokine produced by activated T cells, mast cells, and basophils. It was initially identified as a B cell differentiation factor (BCDF), as well as a B cell stimulatory factor (BSF1). IL-4 has since been shown to have multiple biological effects on hematopoietic and non-hematopoietic cells, including B and T cells, monocytes, macrophages, mast cells, myeloid and erythroid progenitors, fibroblasts, and endothelial cells. Rat, mouse and human IL-4 are species-specific in their activities.
Image: IL-4 staining of frozen tissue sections of human lymph node. Sections were stained using anti-mouse ABC-HRP, NovaRed (red) substrate and Haematoxylin (blue) counterstain.