Cutting Edge: Bispecific γδ T Cell Engager Containing Heterodimeric BTN2A1 and BTN3A1 Promotes Targeted Activation of Vγ9Vδ2+ T Cells in the Presence of Costimulation by CD28 or NKG2D

Abstract

Vγ9Vδ2+ T cell–targeted immunotherapy is of interest to harness its MHC-independent cytotoxic potential against a variety of cancers. Recent studies have identified heterodimeric butyrophilin (BTN) 2A1 and BTN3A1 as the molecular entity providing “signal 1” to the Vγ9Vδ2 TCR, but “signal 2” costimulatory requirements remain unclear. Using a tumor cell–free assay, we demonstrated that a BTN2A1/3A1 heterodimeric fusion protein activated human Vγ9Vδ2+ T cells, but only in the presence of costimulatory signal via CD28 or NK group 2 member D. Nonetheless, addition of a bispecific γδ T cell engager BTN2A1/3A1-Fc-CD19scFv alone enhanced granzyme B–mediated killing of human CD19+ lymphoma cells when cocultured with Vγ9Vδ2+ T cells, suggesting expression of costimulatory ligand(s) on tumor cells is sufficient to satisfy the “signal 2” requirement. These results highlight the parallels of signal 1 and signal 2 requirements in αβ and γδ T cell activation and demonstrate the utility of heterodimeric BTNs to promote targeted activation of γδ T cells.

Division of labor and cooperation between different butyrophilin proteins controls phosphoantigen-mediated activation of human γδ T cells

“…In the new complex, binding of TCRγ (CDR2 and HV4) chain to the C-F-G surface of BTN2A1-V domain would be retained, while other CDRs might additionally interact with the newly formed BTN2A1-BTN3A complex that is in line with the ndings of Willcox research group. A direct interaction of the Vγ9Vδ2 TCR with V-domains of BTN2A1-BTN3A complexes would also be compatible with a most recent report that shows direct stimulation of Vγ9Vδ2 T cells by recombinant BTN3A1-BTN2A1 heteromers in the presence of a co-stimulus 54 . However, it is yet to be proven whether BTN2A1 and BTN3A1 can form a functional heterodimer.…”

Cytokines enhance human Vγ9Vδ2 T‐cell TCR‐dependent and TCR‐independent effector functions

“…We next validated these findings in the K562 cell line, which is targeted by Vδ2 T cells for killing to a lesser extent than Raji cells [28, 31]. Inhibition of BTN3A1 on Vδ2 T cells expanded with zoledronate + IL‐2 alone at an E:T ratio of 5:1 did not inhibit lysis, indicative of a TCR‐independent mechanism of recognition of K562 cells (Supporting information Fig.…”

“…Having established that cytokine plus antigen stimulation of Vδ2 T cells modulates the expression of key surface receptors and cytolytic mediators, we next explored the functional capacity of Vδ2 T cells under these conditions. Utilizing a series of lactate dehydrogenase (LDH) cytotoxicity assays, we assessed Vδ2 T cell‐mediated cytotoxicity of two tumor cell lines (Raji and K562), which are recognized by Vδ2 T cells to varying extents [28].…”

Identification of immune-related genes and development of a prognostic model in mantle cell lymphoma

“…Previous studies have evaluated the expression of several immune checkpoint molecules and explored their effects on the prognosis of MCL and other B-cell lymphomas. The addition of heterodimeric BTN2A1 and BTN3A1 could promote granzyme B-mediated killing of CD19 + lymphoma cells when co-cultured with Vγ9Vδ2 + T cells ( 31 ). Also, CD200 expression in MCL indicated a better prognosis and was associated with CD23 expression, frequent immunoglobulin heavy chain variable region (IGHV) mutations, and the absence of SOX11 expression ( 32 , 33 ).…”