Interleukin 6 (IL-6) is a pleiotropic cytokine that acts as both a proinflammatory and anti-inflammatory mediator. It is secreted by T cells and macrophages to stimulate immune response (eg, during infection and after trauma, especially burns or other tissue damage leading to inflammation). IL-6 has been shown in mice to be required for resistance against the bacterium Streptococcus pneumoniae. IL-6 is an important mediator of fever and the acute phase response that enhances the innate immune system and protects against tissue damage.
IL-6 plays an important role in the early stages of T cell differentiation. IL-6 reinforces the effect of IL-2 and promotes the differentiation of CD4 cells into T-helper cells. IL-6 also affects the growth and proliferation of early progenitor cells in the thymus and bone marrow and is later important in both T cell and natural killer (NK) cell activation.
IL-6 stimulates the differentiation and proliferation of B cells and induces the permanent differentiation of B-cells into plasma cells. IL-6 enhances the release of IgG and IgA antibodies by serving as a growth factor for differentiated plasma cells.
IL-6 is produced by muscle and is elevated in response to muscle contraction. It is significantly elevated with exercise, and precedes the appearance of other cytokines in the circulation. During exercise, it is thought to act in a hormone-like manner to mobilize extracellular substrates and/or substrate delivery. Additionally, osteoblast secrete IL-6 to stimulate osteoclast formation. IL-6 is also produced by adipocytes and is thought to be a reason why obese individuals have higher endogenous levels of C-reactive protein. Il-6 may also affect glucose homeostasis and metabolism directly and indirectly by action on setal muscle cells, adipocytes, hepatocytes, pancreatic β-cells, and neuroendocrine cells.
Red-top tube or gel-barrier tube
Separate serum from cells. Transfer serum to a plastic transport tube.
Stable at room temperature or frozen for 14 days. Freeze/thaw cycles x3.
Gross hemolysis; sample left on cells