Glossary
Cytokine.
Direct answer
A cytokine is a small messenger protein released by one cell to act on others. Cytokines set the onset, strength and ending of inflammation, direct the movement of defence cells, and instruct the liver to produce acute phase proteins. Interleukin 6 and tumour necrosis factor are well known examples.
Cytokines act at very low concentrations, over short distances and usually for a short time. Sorting them into pro-inflammatory and anti-inflammatory groups is a simplification: the same molecule changes effect with tissue, timing and accompanying signals. A single blood value therefore says little about the state of a given tissue.
Cytokines are species specific. An assay built for human interleukin 6 often detects the equine molecule poorly or not at all. Work in horses needs reagents validated for the species, otherwise falsely negative results appear. This obstacle explains why cytokine comparisons between horse and human have to be worded carefully.
Acute inflammationChronic inflammationAcute phase proteinResolution of inflammation
The evidence letter
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