10.01.4 Cytokines

In addition to allergy, cytokines have a role in inflammatory conditions, especially in autoimmune-inflammatory conditions such as rheumatoid arthritis. Cytokines are small secreted proteins that mediate and regulate inflammation, immunity, and haematopoiesis. Cytokines generally act over short distances, short time spans, and at very low concentrations. They act to alter gene expression.

Interleukins (IL) are cytokines made by one leukocyte and acting on other leukocytes. There are many interleukins, but IL-1 is the main one associated with inflammation. IL-1 stimulates T-lymphocytes to produce IL-2, which promotes inflammation, and causes fever. IL-2 stimulates growth and activation of other T cells and NK (natural killer) cells (Figure 10.2).

Anakinra is an IL-1 antagonist used in the severe inflammation associated with rheumatoid arthritis. It is administered subcutaneously. Anakinra commonly causes allergy, and treatment has the possibility of allowing serious infection, as the interleukins also have a major role in immunity (Figure 10.2).

Figure 10.2 Mechanism of action of anakinra (Copyright QUT, Sheila Doggrell)

Tumour necrosis factor (TNF) is the other cytokine that has a prominent role in inflammation. TNF kills tumour cells, and hence the name. TNF stimulates the activities of T cells and eosinophils, which are cells involved in the inflammatory process.

Tumour necrosis factor (TNF) is the other cytokine that has a prominent role in inflammation. Infliximab is an antibody to TNF. Infliximab is administered intravenously, every 8 weeks in the hospital setting. During treatment with infliximab, bacterial infection is infrequent. Infliximab is used in the treatment of rheumatoid arthritis and ankylosing spondylitis (degenerative inflammatory arthritis affecting the spine and sacroiliac joints).