β-Interleukin II (44-56), (C68H113N19O19) is a peptide with the sequence NH2-ILE-LEU-ASN-GLY-ILE-ASN-ASN-TYR-LYS-ASN-PRO-LYS-LEU-COOH, MW= 1500.7. Interleukin 2 (IL-2) belongs to the interleukin family, a type of cytokine signaling molecule in the immune system, and it is a protein that regulates the activities of the white blood cells (leukocytes, often lymphocytes) responsible for immunity. IL-2, a soluble hormone-like mediator of the immune system, was the first interleukin molecule to be identified and characterized. It is necessary for the growth, proliferation, and differentiation of T cells to become 'effector' T cells. IL-2 is normally produced by T cells during an immune response and is necessary for the development of T cell immunologic memory, which depends upon the expansion of the number and function of antigen-selected T cell clones.IL-2 is also necessary for the maturation of a subset of T cells, termed regulatory T cells, during T cell development in the thymus.
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