"A number of participants at the Second International Lymphokine Workshop developed a system of nomenclature based on the elemental property of factors such as LAF and TSF, i.e., their ability to act as communication signals between different populations of leukocytes. Thus, the term Interleukin (between leukocytes) was proposed. LAF was designated Interleukin 1‥and TSF was designated Interleukin 2" (OED).