Cytokines are small hormnone like polypeptides. Produced by a cell, then secreted by that cell, they can then bind to a receptor on the surface of another cell. The binding of a cytokine to a receptor on the surface of another cell intiates a physiological response. Immune cells make many different kinds of cytokines. Often, cytokines can be categorized according to the type of white blood cell that produces them, For example, cytokines produced by lymphocytes are referred to as lymphokines, cytokines produced by monocytes are called monokines.
Interferons protect neighboring cells from invasion by parasites, including viruses.
TNF can act as a direct cytotoxin to tumor cells, also it can induce fever, sleep, stimulate production of other cytokines, activate macrophages and mediate inflmaamtion. CSF can promote the growth of other wbc's. Clinically An elevated total white blood cell count is called leukocytosis, a decreased total wbc count is called leukopenia. Leukocytosis occurs during pregnancy, emotional stress, strenuous exercise, in response to all types of infections, collagen disorders, leukemias, transfusion reactions, parasitic infestations and inflammatory disorders. Any bacterial infection is likely to cause an increase in segmented neutrophils.