What are cytokines?

Cytokines are small proteins that are crucial in controlling the growth and activity of other immune system cells and blood cells. When released, they signal the immune system to do its job. Cytokines affect the growth of all blood cells and other cells that help the body's immune and inflammation responses. Kinds of cytokines include interleukins (produced by leucocytes) lymphokines (produced by lymphocytes), interferons and tumour necrosis factor. Some cytokines are “pro-inflammatory” – i.e. they increase inflammation, while others are “anti-inflammatory” – i.e. reducing inflammation in the body.