∞ generated and posted on 2015.12.30 ∞

Molecules produced by virus-infected and other ailing cells that are used as a means of communicating that situation to other cells so that the latter can take protective actions.

More generally, Interferons are cytokines produced by body cells that are experiencing some form of distress due especially, though not exclusively, to association with pathogens (particularly though not only viruses), and classically these cytokines serve as a warning to nearby body cells of this problem, though immune system cells can be signaled as well by interferons.

The classic scenario of interferon induction and use involves a normal body cell that has been infected by a virus. The cell detects the presence of this virus and then secretes interferon molecules into the interstitial fluid. The interferon molecules serve especially as paracrine factors, signaling neighboring cells of the problem.

The physiological goal of this process is to reduce the potential for those nearby cells to support a subsequent viral infection. Thus, the virus-infected cell at some point will produce virus particles and the primary target for infection by those virus particles are nearby body cells, the same cells that are most likely to be exposed to locally produced interferons.

Interferon binding to these nearby cells induces signal transduction cascades that result in the production of factors that are able to inhibit subsequent viral infection. These factors are not produced constitutively because of the potential for these factors to interfere with the normal functioning of these cells. Cells thus can function normal in the absence of pathogen attack but are able to take on pathogen-resistant state especially when pathogens, such as viruses, are explicitly, locally present within the body.