Butyrophilin 3A1 and Butyrophilin 2A1 complex (BTN3A1/BTN2A1)

The Butyrophilin 3A1 (BTN3A1) and Butyrophilin 2A1 (BTN2A1) complex serves as the primary molecular sensor on tumor cells recognized by Vγ9Vδ2 γδ T cells, a major subset of human unconventional T cells (Laportha et al., 2020 [5]). These T cells do not recognize MHC-presented peptides but instead respond to phosphoantigens (PAgs) like isopentenyl pyrophosphate (IPP), which are frequently elevated in cancer cells due to dysregulated metabolism (Vantourout et al., 2013 [3]). BTN3A1 acts as an intracellular sensor for PAgs via its B30.2 domain, while BTN2A1 is essential for the direct binding and activation of the Vγ9Vδ2 T-cell receptor (TCR) (Rigau et al., 2020 [1]; Karunakaran et al., 2020 [2]). This interaction triggers potent γδ T cell-mediated cytotoxicity and cytokine production against the tumor. Therapeutic targeting of this complex, such as with the monoclonal antibody ICT01, aims to bypass the requirement for high PAg levels to activate the immune system against various malignancies (ImCheck Therapeutics [4]). Understanding the interplay between these butyrophilins is critical for developing next-generation immunotherapies that leverage the innate-like properties of γδ T cells.

Other names

CD277BTN3A1BTN2A1Phosphoantigen-presenting complexVγ9Vδ2 TCR ligandsButyrophilin subfamily 3 member A1Butyrophilin subfamily 2 member A1

Activation of Vγ9Vδ2 T cells through the induction of a conformational change or clustering of the BTN3A1/BTN2A1 complex on the target cell surface, which is typically triggered by the binding of intracellular phosphoantigens to the BTN3A1 B30.2 domain (Rigau et al., 2020 [1]; Vantourout et al., 2013 [3]).