Cytokine

Thus, in the case of viral infection, mechanisms of resistance would be threefold, namely, interferon production, the immune response, including both antibody and lymphokine production, and the generation of lymphokine-like substances by the infected cells themselves. These latter substances have been defined as cytokines.

A fundamental feature expressed by the vast majority of cytokines is a profound immunomodulatory activity. Many cytokines, presently available in pure recombinant form, modify bone cell metabolism.

The cytokines are generally considered to be a group of peptides secreted by cells of the immune system such as macrophages, lymphocytes and T cells, although the same peptides may also be secreted by non-immune cells such as neurological tissues and adipocytes.

The cytokines provide a classic example of products of the immune system which alter brain and endocrine activities. A variety of cytokines, including interleukin 1, interleukin 2, interleukin 6, and tumor necrosis factor α, have been traditionally associated with peripheral control of the immune system, inflammation, and acute phase response.

Surprisingly, mTOR inhibitors displayed little inhibitory efficacy regarding receptor modulation and cytokine production which may be clinically relevant in terms of the risk of underimmunosuppression with this class of drugs.