Mónica Adriana Rodríguez-Cadena

The γδ T cells belong to a subgroup of T cells known as non-conventional T cells due to their limited T cell receptor (TCR) repertoire and ability to recognize non-peptide antigens. They play a crucial role in combating infections and tumors. Vγ9Vδ2 T cells are typically activated by molecules containing diphosphate groups, collectively known as phosphoantigens (pAgs), through a non-canonical mechanism which involves the intracellular domain of butyrofilin (BTN)3A1 protein. However, no FDA-approved drugs have yet been shown to activate them, and the underlying cellular mechanisms remain unknown. In this study, we combined high-throughput virtual screening of an FDA-approved drug database with in vitro cellular assays to identify potential γδ T cells activators. Our findings demonstrate that Nitazoxanide (NTZ) and Tinidazole induce moderate elicited a statistically significant increase in interferon (IFN)-γ production of Vγ9Vδ2 T cells by their probably interaction with the pAg binding site of BTN3A1. Additionally, NTZ induces expression of CD107a, but only at the highest concentrations tested and promotes the upregulation of HLA-DR in total PBMCs and CD14⁺ monocytes. Blocking BTN3A with a specific antibody led to a marked reduction in all NTZ-induced activations. This work identifies NTZ as a previously unrecognized activator of γδ T cells, highlighting its immunomodulatory potential beyond its known clinical uses. These findings broaden our understanding of γδ T cells pharmacology and suggest new opportunities for drug repurposing and the design of novel chemical scaffolds. Further mechanistic studies will be essential to fully define how NTZ engages the BTN3A–γδ T cells axis.