High Sensitivity Cytokine ELISA Kits & Multiplex Panels

Cytokines are cell signalling molecules that promote cell communication in immune responses. They also stimulate the movement of cells towards sites of inflammation and infection. Cytokines can be in peptide, protein and glycoprotein forms. The cytokines are a large family of molecules that are classified in various different ways. Cytokines are produced throughout the body and must bind to their proprietary receptor in order to become activated.

Cytokines can carry out varying functions depending on their activity with their receptor, they can exhibit autocrine, paracrine or endocrine activity:

• Autocrine action: by binding to the receptor on the membrane of the same cell that produced the cytokine.
  
  
• Paracrine action: binding to receptors on a target cell nearby to the cell that produced the cytokine.
  
  
• Endocrine activity: traveling through circulation and acting on target cells in more distant areas of the body.

There are many types of cytokines, including chemokines, interferons, interleukins, lymphokines, and tumour necrosis factor . They are produced by a vast range of cells, including immune cells such as macrophages, B cells, T cells, mast cells, endothelial cells, fibroblasts, and various stromal cells. Certain cytokines can be produced from more than one cell type. Cytokines can be classified as pro-inflammatory cytokines or anti-inflammatory cytokines depending on whether they promote inflammation at the site of infection or cause a reduction of the inflammation produced.

Many cytokines have names which begin with the word 'interleukin'. This is because cytokines were originally discovered in the context of signalling between (inter) immune cells (leukins). Interleukins can facilitate cell growth, differentiation, maturation, or proliferation, depending on the context.

Cytokines are key players in the generation, and later, inhibition of immune responses. Pro-inflammatory cytokines like IL-1 and TNFα can drive an inflammatory response forward and recruit appropriate cells to a site. These cytokines can play a pathogenic role in chronic or acute inflammatory diseases. Anti-inflammatory cytokines like IL-10 and TBF-β have the opposite effect, and are implicated in the resolution of inflammation and the restoration of homeostasis. However, they too can play a pathogenic role when their inflammatory-suppressing action is used to create a tolerogenic immune environment in tumours.

With the need for researchers to analyse low levels of cytokines in cell culture, macrophage polarization or physiological assays, Assay Genie has developed a range of highly sensitive cytokine ELISA assays to measure key cytokines such as IL-2, IL-4, IL-6, IL-10, IL-12p70 & Interferon gamma at pg/mL levels.

Because cytokines are primarily peptides or otherwise hydrophilic, they cannot cross cell membranes and instead rely on the receptors. The cytokine-receptor interaction has been the target of considerable therapeutic interest. In fact, some of the most popular drugs on the market are biologics which act on cytokines. A notable example includes the anti-TNFα monoclonal antibody adalimumab, which works by binding and blocking the pro-inflammatory TNFα. Since the cytokine plays a role in the severity of such inflammatory diseases as rheumatoid arthritis, reducing the levels of soluble TNFα can significantly attenuate the immune response and halt further downstream effects.

Etanercept also acts on the cytokine TNFα and is a fine example of cytokine manipulation applied to a therapeutic context. Etanercept is a fusion protein modeled after the naturally occurring soluble TNF receptor. It is able to bind TNFα— effectively ‘mopping it up’ from the affected areas— and because of its unique protein composition it is much more robust and long-lasting in the bloodstream than unaltered soluble TNF receptors. Both it and adalimumab have met with impressive clinical and commercial success since their release.

Cytokines play complex and context-dependent roles in the immune system. A single cytokine can have vastly different effects depending on the cell type or signalling pathway activated. For example, IL-4 has been reported to be involved in airway inflammation in patients with allergic asthma, but it can also induce differentiation in naive helper T cells and facilitate their development into Th2 helper T cells. Another important interleukin, IL-2, is primarily produced by activated cytotoxic CD8+ T cells and active CD4+ helper T cells. IL-2 can promote the differentiation of immature T cells to regulatory T cells in the thymus, thus aiding in the resolution of inflammation and preventing autoimmune diseases. Rather paradoxically, IL-2 can also encourage T cells to differentiate into effector and memory T cells after initial exposure to their cognate antigen. Despite its generally helpful role, IL-2 has been implicated in psoriasis.

Therefore Assay Genie have developed a range of multiplex assays called, Genieplex, to identify key signalling pathways involved in cytokine and signalling. Geniplex allows researchers to measure up to 24 analytes at once using as little as 15uL of sample.