IL 2 Human, Yeast

Interleukin-2 (IL-2) is a type of cytokine signaling molecule that plays a crucial role in the immune system. It is primarily involved in the proliferation and differentiation of T and B lymphocytes, which are essential for the body’s immune defense against infections . IL-2 is a protein with a molecular weight of approximately 15.5 to 16 kDa .

Human recombinant IL-2 can be produced using various expression systems, including yeast. The yeast expression system is often preferred due to its ability to perform post-translational modifications and its relatively high yield of protein production. The recombinant IL-2 produced in yeast is a single, non-glycosylated polypeptide chain containing 133 amino acids .

The preparation of human recombinant IL-2 involves several steps:

1. Gene Cloning: The gene encoding IL-2 is cloned into an expression vector suitable for yeast.
2. Transformation: The expression vector is introduced into yeast cells, which are then cultured under conditions that promote the expression of IL-2.
3. Purification: The IL-2 protein is purified using chromatographic techniques to achieve a high level of purity, typically greater than 97% .
4. Lyophilization: The purified IL-2 is lyophilized (freeze-dried) to form a sterile, white powder that can be reconstituted in sterile distilled water for use .

IL-2 interacts with its receptor, a heterotrimeric protein complex, to exert its biological effects. The receptor’s gamma chain is shared by other interleukins, such as IL-4 and IL-7 . The binding of IL-2 to its receptor triggers a cascade of intracellular signaling events that lead to the proliferation and activation of T and B lymphocytes.

Additionally, IL-2 has been shown to bind to sulfated polysaccharides such as heparin and heparan sulfate. This binding is dependent on the length of the heparin chain, with fragments as small as 15-mers retaining binding activity . The interaction with heparin does not interfere with IL-2’s ability to bind to its receptor, suggesting that heparin may help retain IL-2 in an active form close to its site of secretion .

The biological activity of IL-2 is measured by its ability to stimulate the proliferation of IL-2 dependent cells. The specific activity of recombinant IL-2 is typically determined using assays that measure the dose-dependent stimulation of murine CTLL-2 cells . The effective dose (ED50) for IL-2 is less than 0.1 ng/ml, corresponding to a specific activity of 1x10^7 IU/mg .