Wednesday, March 7, 2012
Cytokinins are a class of plant growth substances that promote cell division, or cytokinesis from the Greek cyto- (cell) and kinesis (motion, movement), in plants. Kinetin is an example and so is zeatin (pictured, found in maize).
Cytokines from the Greek cyto-, (cell); and -kinos, (movement) are small cell-signaling protein molecules that are secreted by numerous cells of animal immune systems and are a category of signaling molecules used extensively in intercellular communication. Although they have a rather wide variety of effects they do sometimes trigger differentiation of cells. The most widely known cytokines are the various interferons.
So both animals and plants use signalling molecules to stimulate cell division. In animals the term 'Cytokine' is now used more broadly and encompasses compounds that don't just lead to cell division. As far as I am aware the specific compounds used by animals and plants are completely different - the name Cytokinin/Cytokine describes a function rather than a specific molecular structure so I suppose its possible there is a compound that acts as both a cytokinin in plants and a cytokine in animals. There are about 200 compounds classified as Cytokinins and, I think, a somewhat larger number of Cytokines.