Cytokine

Cytokines are small proteins important in cell signaling that modulate the immune system.

There are lots of different cytokines and they are complex to understand. The quickest explanation is that they are messenger molecules passing information around the body. They are a bit like hormones in this way, but they are usually communicating in response to something external and lead to inflammatory or immune responses. When reading cytokine studies it is important to remember that with so many cytokines it is common to find some pattern and results can change quickly within individuals. In a small sample, if just a couple of people were fighting a cold then this could change the overall results.

Types of cytokines
chemokines

interferons

interleukins

lymphokines

tumor necrosis factor

Cellular immune response
IFN-γ TNFα

Antibody response
TGF-β, IL-4, IL-10, IL-13

Cytokines in Chronic Fatigue Syndrome
There is increasing evidence that cytokine expression is altered in CFS (ME). Two studies in 2015 found a general pattern of down regulation in long term patients (Hornig et al [Distinct plasma immune signatures in ME/CFS are present early in the course of illness ]