Overexpression and structure--function analysis of a bioengineered IL-2/IL-6 chimeric lymphokine

Area of Science:

• Immunology
• Molecular Biology
• Biotechnology

Background:

• Interleukin-2 (IL-2) is crucial for cellular immunity, while Interleukin-6 (IL-6) modulates humoral responses.
• Engineering bifunctional lymphokines can create novel immunomodulatory agents.

Purpose of the Study:

• To synthesize and characterize a novel bifunctional lymphokine combining IL-2 and IL-6.
• To assess the refolding, stability, and biological activity of the engineered fusion protein.
• To evaluate the potential therapeutic applications of this dual-action immunomodulator.

Main Methods:

• A synthetic chimeric IL-2/IL-6 gene was constructed and overexpressed in Escherichia coli.
• Inclusion bodies were denatured, refolded, and reoxidized; the fusion protein (rIL-2/IL-6) was purified.
• A collagen-like spacer allowed for cleavage into functional IL-2 and IL-6 subunits.

Main Results:

• The purified rIL-2/IL-6 fusion protein reacted with specific antisera for both IL-2 and IL-6.
• Cleaved subunits were correctly reoxidized and retained full activity comparable to native counterparts.
• Circular dichroism confirmed proper refolding and alpha-helical structures for both cytokine moieties.
• The chimera exhibited potent IL-2 activity in cell proliferation assays and IL-6 activity in B-cell and hepatocyte function assays.

Conclusions:

• The engineered bifunctional lymphokine (rIL-2/IL-6) is stable, biologically active, and possesses dual IL-2 and IL-6 functions.
• This fusion protein can amplify cellular and humoral immune responses, indicating therapeutic potential.
• The developed lymphokine may serve as an effective immunomodulator for enhancing host responses, particularly in vaccination strategies.