IL-21是什么?

懒得写了，粘贴一下吧!~!
Interleukins are a group of cytokines (secreted signaling molecules) that were first seen to be expressed by white blood cells (leukocytes, hence the -leukin) as a means of communication (inter-). The name is something of a relic though (the term was coined by Dr. Paetkau, University of Victoria); it has since been found that interleukins are produced by a wide variety of bodily cells. The function of the immune system depends in a large part on interleukins, and rare deficiencies of a number of them have been described, all featuring autoimmune diseases or immune deficiency.

Name Source Function
IL-1 macrophages small amounts induce acute phase reaction, large amounts induce fever.
IL-2 TH1-cells stimulates growth and differentiation of T cell response. Can be used in immunotherapy to treat cancer or suppressed for transplant patients.
IL-3 T cells stimulates bone marrow stem cells
IL-4 TH2-cells, just activated naive CD4+ cell,