Expression, Identification and Characterize of CD25-Binding Epitope Modified Human IL-2 in Pichia pastoris.

Interleukin-2 (IL-2) plays important roles in variety of immune functions and it is widely used in the medication. But in recent years it was reported that vascular leak syndrome (VLS) was induced by IL-2. Evidences showed that the interaction of IL-2 and IL-2Rαβγ (CD25) caused VLS. Thus, this experiment modified the CD25-binding epitope in human IL-2 (hIL-2) to minimize the side effect of IL-2 in the medication. In this study, a recombinant human interleukin 2 (rhIL-2) was expressed in Pichia (P.) pastoris. An effective strategy was established to express rhIL-2 protein in 120 L scale and the optimal purification procedure was investigated. The purity of rhIL-2 in final product was about 98 % and the concentration of the rhIL-2 was 0.45 mg/mL. Bioactivity analysis showed that the purified rhIL-2 protein displayed high activity on proliferation of CTLL-2 cells and increased the ratio of CD4(+)/CD8(+). It indicates that the target protein is expressed and the character of the rhIL-2 has high activity. This study provides a strategy for large-scale production of bioactive rhIL-2 protein using P. pastoris as an expression host.