Anti-CD8/IL-15 (N72D)/sushi fusion protein: A promising strategy for improvement of cancer immunotherapy.

Abstract

Background: To overcome the limitations of IL-15 and to improve the efficacy of IL-15 in immunotherapy, several strategies have been introduced.

Objective: The objective of this study was to generate and evaluate a novel anti-CD8/IL-15 (N72D)/Sushi fusion protein with the potential to target CD8⁺ T cells and enhance functionality of CD8⁺ T cells against tumor cells.

Methods: In this connection, a novel fusokine that contains IL-15(N72D), a Sushi domain, and anti-CD8 single-chain fragment variable (scFv) was designed. The size accuracy and binding potency of the isolated protein were assessed using western blotting and indirect surface staining. Following purification, the potential function of the anti-CD8/IL-15(N72D)/Sushi fusion protein in the induction of proliferation and cytotoxicity of CD8⁺ T cells was evaluated.

Results: In-silico analysis revealed that fusokine is structurally stable, correctly folded and can interact with the CD8 co-receptor. Both fusokine and IL-15(N72D)/Sushi were produced in CHO-S cell line with a final concentration of 18.43 mg/l and 12.64 mg/l respectively. Fusokine bound to 97.6 % of CD8⁺ T cells and significantly induced T cell proliferation and cytotoxic potential in peripheral blood mononuclear cells (PBMCs) in a time dependent manner. Compared to both the control and the IL-15 (N72D)/sushi treated groups, fusokine showed superior potential in CD8⁺ T cell functionality.

Conclusion: Anti-CD8/IL-15(N72D)/Sushi has the ability to effectively target CD8⁺ T cells, promote lymphocyte proliferation and induce cytotoxicity against tumor cells. Due to its promising properties, it could be considered as a new potential immunotherapy approach.