Functional and structural similarity of Vγ9Vδ2 T cells in humans and Aotus monkeys, a primate infection model for Plasmodium falciparum malaria

gamma delta T cells are implicated to play crucial roles during early immune responses to pathogens. A subset of human gamma delta T cells carrying the V-gamma 9V delta2 TCR recognize small, phosphorylated nonpeptidic Ags. However, the precise role of these cells and the ligands recognized in human immune responses against pathogens remains unclear because of the lack of suitable animal models. We have analyzed the reactivity of spleen cells of the New World monkey Aotus nancymaae against isopentenyl pyrophosphate (IPP), a phosphorylated microbial metabolite selectively activating V gamma 9V delta2 T cells. Spleen cells were stimulated by IPP and the expanding cell population expressed the V gamma9 TCR. TRGV-J and TRDV-D-J rearrangements expressed by IPP-stimulated cells of Aotus were analyzed by RT-PCR and DNA sequencing. The TRGV-J and TRDV-D-J rearrangements expressed by IPP-stimulated Aotus and human gamma delta T cells were similar with respect to 1) TCR gene segment usage, 2) a high degree of germline sequence homology of the TCR gene segments used, and 3) the diversity of the CDR3 regions. Phylogenetic analysis of human, Pan troglodytes, and A. nancymaae TRGV gene segments showed that the interspecies differences are smaller than the intraspecies differences with TRGV9 gene segments located on a distinct clade of the phylogenetic tree. The structural and functional conservation of V gamma 9V delta2 T cells in A. nancymaae and humans implicates a functionally important and evolutionary conserved mechanism of recognition of phosphorylated microbial metabolites.