“Interleukins are a group of cytokines (secreted proteins and signaling molecules) that were first seen to be expressed by white blood cells (leukocytes). The function of the immune system depends in a large part on interleukins, and rare deficiencies of a number of them have been described, all featuring autoimmune diseases or immune deficiency. The majority of interleukins are synthesized by helper CD4 T lymphocytes, as well as through monocytes, macrophages, and endothelial cells. They promote the development and differentiation of T and B lymphocytes, and hematopoietic cells. Interleukin receptors on astrocytes in the hippocampus are also known to be involved in the development of spatial memories in mice. Common families of interleukins: Interleukin 1, Interleukin 2, Interleukin 3, Interleukin 4, Interleukin 5, Interleukin 6, Interleukins 7 and 9, Interleukin 8, Interleukin 10, Interleukin 11, Interleukin 12, Interleukin 13, Interleukin 15, Interleukin 17.”