Interleukin-2 Unit Converter

Interleukin-2 (IL-2) is a signaling protein called a cytokine that plays a central role in regulating the immune system. It was originally discovered as "T-cell growth factor" because of its ability to stimulate T cells to multiply.

When measured in blood, IL-2 reflects the degree of immune activation occurring in the body. In healthy individuals, serum IL-2 is very low (at or below about 2.1 pg/mL), so a detectable rise typically signals that the immune system is actively responding to something.

IL-2 has a dual nature: at higher concentrations it drives immune attack by expanding effector T cells and natural killer (NK) cells, while at lower concentrations it preferentially supports regulatory T cells (Tregs) that keep the immune system in check.

IL-2 is produced primarily by activated CD4+ T helper cells, with smaller contributions from CD8+ T cells, dendritic cells, NK cells, and certain other immune cells.