Vγ9Vδ2 T cells expanded with Vitamin C combined with HMBPP in vitro inhibit intracellular Mycobacterium tuberculosis growth

Shuyan Liu ¹ Xiao Guo Hui ¹ Wanxin Liang ¹ Su Zhang ¹ Juan Liang ¹ Teng Pan ² Shaoxiang Liu ² Xiuju Liu ² Zhenwen Zhou ^2* Guoliang Zhang ^1*

• ¹ Shenzhen Third People’s Hospital, Shenzhen, Guangdong Province, China
• ² Shenzhen Longgang District Maternal and Child Health Care Hospital, Shenzhen, China

Background: HMBPP-activated Vγ9Vδ2 T cells potently inhibit the growth of intracellular BCG or Mycobacterium tuberculosis (Mtb). Vitamin C (VC) has been shown to promote the differentiation and proliferation of human purified Vγ9Vδ2 T cells stimulated with HMBPP or restimulated with 14-day-expanded γδ T cells. In this study, we investigated whether VC enhances the expansion of Vγ9Vδ2 T cells within PBMCs primary activated by HMBPP combined with recombinant IL-2(rIL-2). Additionally, we explored the inhibition effects and underlying mechanisms of Vγ9Vδ2 T cells expanded with HMBPP, VC, and rIL-2 on intracellular Mtb growth. Results: Our findings demonstrated that vitamin C (70 μM) significantly enhances the expansion of Vγ9Vδ2 T cells within PBMCs during primary HMBPP activation in the presence of rIL-2, compared to induction with HMBPP and rIL-2 alone. Both the induction rate and total cell proliferation were significantly higher in the VC-treated group. By day 14 of induction, Vγ9Vδ2 T cells expanded with HMBPP, VC, and rIL-2 exhibited the central memory (10-20%) and the effector memory phenotypes (75-90%). Furthermore, these cells effectively inhibited the growth of intracellular virulent strain (H37Rv) in a cell-contact-dependent manner. This inhibition was associated with significantly upregulated the production of TNF-α and IFN-γ, and downregulated expression of IL-10 and IL-17A during Mtb infection. Conclusion: Our study demonstrates that VC enhances the proliferative expansion of Vγ9Vδ2 T cells within PBMCs primarily stimulated with HMBPP and rIL-2. The expanded Vγ9Vδ2 T cells effectively inhibit the growth of virulent H37Rv strain, likely through the secretion of TNF-α and IFN-γ. These findings provide a novel research direction for the development of tuberculosis treatment.