A cloned chicken lymphokine homologous to both mammalian IL-2 and IL-15.

IL-2, cloned in several mammalian species, plays a critical role in immune system function. Indirect evidence suggests that IL-2-like molecules also exist in lower vertebrates, although none has been cloned. In view of the commercial importance of poultry and the lack of any IL-2 sequence data in lower vertebrates, we undertook to clone a chicken IL-2-like molecule.