Interleukin 3

Interleukin 3 (IL-3) is a protein that in humans is encoded by the IL3 gene.

Function

Interleukin 3 is an interleukin, a type of biological signal (cytokine) that can improve the body's natural response to disease as part of the immune system. It acts by binding to the interleukin-3 receptor.

Interleukin 3 stimulates the differentiation of multipotent hematopoietic stem cells into myeloid progenitor cells or, with the addition of IL-7, into lymphoid progenitor cells. In addition, IL-3 stimulates proliferation of all cells in the myeloid lineage (granulocytes, monocytes, and dendritic cells), in conjunction with other cytokines, e.g., Erythropoietin (EPO), Granulocyte macrophage colony-stimulating factor (GM-CSF), and IL-6. It is secreted by basophils and activated T cells to support growth and differentiation of T cells from the bone marrow in an immune response. Activated T cells can either induce their own proliferation and differentiation (autocrine signalling), or that of other T cells (paracrine signalling) - both involve IL-2 binding to the IL-2 receptor on T cells (upregulated upon cell activation, under the induction of macrophage-secreted IL-1). The human IL-3 gene encodes a protein 152 amino acids long, and the naturally occurring IL-3 is glycosylated. The human IL-3 gene is located on chromosome 5, only 9 kilobases from the GM-CSF gene, and its function is quite similar to GM-CSF.

Discovery

Interleukin 3 originally was discovered by JN Ihle in mice. He found a T cell derived factor that induced the synthesis of 20alpha-hydroxysteroid dehydrogenase in hematopoietic cells and termed it interleukin-3.

Interactions

Interleukin 3 has been shown to interact with IL3RA.

See also

• Interleukin