Cytokines are a group of immune hormones, formed of small proteins involved in activating cells with cytokine receptors.
Chemokines are one type of cytokine, involved in the chemotactic response. This helps increase the concentration of immune cells at the site of infection.
Interferons are secreted by virally-infected cells, allowing them to inform their neighbours of the risk and to improve the anti-viral defences.
Tumour necrosis factor, TNF, is a pro-inflammatory cytokine used to induce an inflammatory response. TNF can kill some cells, and is seen in sepsis infections.
All of these factors are involved in increasing an immune response to a pathogen.