The adipokines, or adipocytokines (Greek adipo-, fat; cytos-, cell; and -kinos, movement) are cytokines (cell signaling proteins) secreted by adipose tissue. The first adipokine to be discovered was leptin in 1994.
Since that time, hundreds of adipokines have been discovered.
monocyte chemotactic protein-1 (MCP-1)
plasminogen activator inhibitor-1 (PAI-1)
retinol binding protein 4 (RBP4)
tumor necrosis factor-alpha (TNFα)
interleukin 8 (IL-8)
interleukin 10 (IL-10)
interferon gamma (IFN-γ)
inducible protein 10 (IP-10 or CXCL10) have been shown to be associated with excessive body weight.
As of 2008, the current terminology refers to a cytokine as an immunomodulating agent. However, conflicting data exists about what is termed a cytokine and what is termed a hormone and more research is needed in this area of defining cytokines and hormones. Under the current terminology, adiponectin, leptin (Ob ligand), and resistin are not appropriately considered adipokines (cytokines) as they do not act on the immune system. (Harrison's Principles of Internal Medicine). Often, these peptides (adiponectin, leptin, and resistin) are referred to as adipokines, however they can be more accurately put into the larger, growing list of adipose-derived hormones.