MOLECULES

Full name: Interleukin-2

Aliases: TCGF and lymphokine¹

Size: 15.5–16.0 kDa^2,3

Family: IL-2 family (IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21)³

Receptors: IL-2 receptor³

Major cellular sources: Activated CD4+ and CD8+ T cells, naïve T cells, NK cells, NKT cells, DCs, and mast cells^2-4

Major cellular targets: CD4+ and CD8+ T cells, B cells, NK cells, and ILCs³

Disease states associated with: Immune diseases, inflammation, autoimmune diseases, inflammatory bowel disease, and allograft rejection^2,5

Major physiologic functions:

• IL-2 plays a key role in immune responses.⁵
• Members of the IL-2 family bind to a shared gamma chain receptor, function primarily as growth and proliferation factors for progenitors, and mature cells and have roles in lineage-specific cell differentiation.³
• IL-2 is essential for the development, differentiation, and maintenance of Treg cells.^5,6
• IL-2 functions as a B-cell growth factor and stimulates antibody synthesis.³
• IL-2 promotes the proliferation and differentiation of NK cells, including increased cytolytic functions.³
• IL-2 limits inflammation by inhibiting Th17-cell differentiation.⁵
• IL-2 promotes the development of Tfh cells, a subset of T cells that controls humoral immune responses.⁵

CD: cluster of differentiation; DC: dendritic cell; IL: interleukin; ILC: innate lymphoid cell; NK: natural killer; NKT: natural killer T; TCGF: T-cell growth factor; Tfh: T follicular helper; Th: T helper; Treg: regulatory T.