Interleukin 5

Interleukin 5 (IL-5) is a cytokine that acts as a key regulator in the life cycle of eosinophil cells, a type of white blood cell that plays a significant role in the human immune system. IL-5 is produced by type 2 helper T cells (Th2 cells) and mast cells. It is part of the interleukin family, a group of cytokines with various functions in the immune system.

Structure

Interleukin 5 is a 52 kDa protein composed of two identical subunits, each with a length of 133 amino acids. The structure of IL-5 is similar to that of other cytokines in the interleukin family, with a four-helix bundle configuration.

Function

IL-5 plays a crucial role in the stimulation of B cell growth and increase in immunoglobulin secretion. It is primarily involved in the activation of eosinophil production during allergic reactions and parasitic infections. IL-5 induces eosinophil differentiation in the bone marrow, stimulates eosinophil release into the bloodstream, and activates mature eosinophils.

Clinical Significance

Due to its role in eosinophil activation, IL-5 has been implicated in a number of eosinophil-related diseases, including asthma, eosinophilic esophagitis, and hypereosinophilic syndrome. In these conditions, the overproduction of IL-5 leads to an excessive number of eosinophils, which can cause inflammation and damage to tissues.

Therapeutic Use

Several drugs have been developed to target IL-5 in the treatment of eosinophil-related diseases. These include mepolizumab and reslizumab, which are monoclonal antibodies that bind to IL-5 and prevent it from interacting with its receptor on the surface of eosinophils.

See Also

• Interleukin
• Cytokine
• Eosinophil
• Mepolizumab
• Reslizumab