Neem leaf glycoprotein promotes dual generation of central and effector memory CD8+ T cells against sarcoma antigen vaccine to induce protective anti-tumor immunity

• Adjuvant help from NLGP generates more number of SarAg specific CD8+ T cells.
• SarAg + NLGP vaccination generates predominantly central and effector memory cells in lymph nodes and spleen respectively.
• NLGP assisted generation of central memory CD8+ T cells is due to mTOR/AKT downregulation and KLF2/FOXO3 upregulation.
• SarAg + NLGP vaccination induced central and effector memory CD8+ T cells show better functionality on antigen re-encounter.

We have previously shown that Neem Leaf Glycoprotein (NLGP) mediates sustained tumor protection by activating host immune response. Now we report that adjuvant help from NLGP predominantly generates CD44+CD62LhighCCR7high central memory (TCM; in lymph node) and CD44+CD62LlowCCR7low effector memory (TEM; in spleen) CD8+ T cells of Swiss mice after vaccination with sarcoma antigen (SarAg). Generated TCM and TEM participated either to replenish memory cell pool for sustained disease free states or in rapid tumor eradication respectively. TCM generated after SarAg + NLGP vaccination underwent significant proliferation and IL-2 secretion following SarAg re-stimulation. Furthermore, SarAg + NLGP vaccination helps in greater survival of the memory precursor effector cells at the peak of the effector response and their maintenance as mature memory cells, in comparison to single modality treatment. Such response is corroborated with the reduced phosphorylation of FOXO in the cytosol and increased KLF2 in the nucleus associated with enhanced CD62L, CCR7 expression of lymph node-resident CD8+ T cells. However, spleen-resident CD8+ T memory cells show superior efficacy for immediate memory-to-effector cell conversion. The data support in all aspects that SarAg + NLGP demonstrate superiority than SarAg vaccination alone that benefits the host by rapid effector functions whenever required, whereas, central-memory cells are thought to replenish the memory cell pool for ultimate sustained disease free survival till 60 days following post-vaccination tumor inoculation.