cytokine
Chapter: 3
A vast array of relatively low molecular weight, pharmacologically active proteins that are secreted by one cell for the purpose of altering either its own functions (autocrine effect) or those of adjacent cells (paracrine effect). In some instances, cytokines enter the circulation and have one or more of their effects systemically. TNF-alpha is an example of a cytokine that can have the latter kinds of effects. In many instances, individual cytokines have multiple biological activities. Different cytokines can also have the same activity, which provides for functional redundancy within the inflammatory and immune systems, i.e., it is infrequent that loss or neutralization of one cytokine will markedly interfere with either of these systems. This fact has great significance in the development of therapeutic strategies. Among the cytokine group are a large number of interleukins plus growth and colony-stimulating factors.
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