Interleukin-13 Unit Converter

Interleukin-13 (IL-13) is a signaling protein called a cytokine that plays a central role in type 2 immune responses. It helps coordinate the body's defense against parasites and is heavily involved in allergic inflammation.

A serum IL-13 test measures the circulating concentration of this cytokine in the blood. Because IL-13 is primarily produced and consumed locally at sites of inflammation, circulating levels are typically very low in healthy individuals.

IL-13 is closely related to interleukin-4 (IL-4), and the two cytokines share a receptor chain and overlapping functions. Elevated serum IL-13 reflects systemic spillover from local type 2 inflammatory activity.

IL-13 is produced by several types of immune cells, primarily Th2 helper T cells and group 2 innate lymphoid cells (ILC2s). Mast cells, basophils, eosinophils, and natural killer cells also contribute, particularly at sites of allergic or parasitic inflammation.