As the name implies, a variable is something which can change. A variable is a way of referring to a memory location used by a computer program. A variable is a symbolic name for this physical location. This memory location contains values, like numbers, text or more complicated types.
The term cytokine is derived from a combination of two Greek words - cyto meaning cell and kinos meaning movement. Cytokines are cell signalling molecules that aid cell to cell communication in immune responses and stimulate the movement of cells towards sites of inflammation, infection and trauma. Cytokines exist in peptide, protein and glycoprotein (proteins with a sugar attached) forms.
Examples of cytokines include the agents interleukin and the interferon which are involved in regulating the immune system's response to inflammation and infection. There is debate among experts over whether certain molecules should be called hormones or cytokines.