An assessment of common marmoset (Callithrix jacchus) γ9+ T cells and their response to phosphoantigen in vitro

γ9δ2 T cells are a primate-specific γδ T cell subtype that expand and become activated during infection, responding directly to phosphoantigens which are by-products of essential metabolic pathways in both bacteria and mammals. Analogues of natural phosphoantigens have been developed as potential immunotherapeutics for treatment of tumours and infectious diseases. Several non-human primate models have been used in preclinical studies, however, little is known about marmoset γ9δ2 T cell responses. We identified γ9+ T cells in various tissues in the marmoset and determined that these cells respond to phosphoantigen in a similar manner to human γ9δ2 T cells in vitro. Both human γ9δ2 T cells and marmoset γ9+ T cells were able to reduce growth of the intracellular bacterium Burkholderia pseudomallei in vitro following expansion with phosphoantigen. This suggests that the marmoset is an appropriate model for examining the immunotherapeutic potential of compounds which target γ9δ2 T cells.