Cloning and Expression of Human Interleukin 2 (IL-2) in E. coli and its Antitumor Activity.

Interleukin 2, also known as T cell growth factor, brought a great revolution in the field of immunology. IL-2 is a pleiotropic cytokine and one of the cytokines that is approved by FDA for cancer immunotherapy particularly kidney and skin cancer. Interleukin-2 (IL-2) is a 4-helix-bundle type I cytokine possessing a cytokine receptor chain essential for the immune response. The current study presents a vector/host combination (pET28a(+)/IL-2) and optimization of expression in LB, TB and M9 media with varying concentrations of inducers (IPTG and lactose) and post induction time. Maximum expression of IL-2 was achieved in LB with 0.5 mM IPTG for 6 hours post induction time. A denaturing purification scheme (Immobilized metal affinity chromatography) was employed for the purification of IL-2. The refolding of the purified IL-2 was achieved by stepwise dialysis method using urea gradient (8M-0M). Human IL-2 was recovered from 1 litre culture to a purity level of ~95%. In vitro cytotoxic potential of IL-2 on HepG-2 and MCF-7 cell lines revealed that it possess sufficient cytotoxic potential and can inhibit the growth of these cell lines directly. Thus, refolded IL-2 had activity identical to that of authentic IL-2 and enhanced the anti-tumor activity of HepG-2 as compared to MCF-7 cells. These conclusions suggest the potential use of the refolded cytokine as immunotherapeutic agent for treatment of hepatocellular carcinoma. [ABSTRACT FROM AUTHOR]