Definition of APC presentation of phosphoantigen (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate to Vγ2Vδ2 TCR

Although microbial (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP) can activate primate V gamma 2V delta 2 T cells, molecular mechanisms by which HMBPP interacts with V gamma 2V delta 2 T cells remain poorly characterized. Here, we developed soluble, tetrameric V gamma 2V delta 2 TCR of rhesus macaques to define HMBPP/APC interaction with V gamma 2V delta 2 TCR. While exogenous HMBPP was associated with APC membrane in an appreciable affinity, the membrane-associated HMBPP readily bound to the V gamma 2V delta 2 TCR tetramer. The V gamma 2V delta 2 TCR tetramer was shown to bind stably to HMBPP presented on membrane by various APC cell lines from humans and nonhuman primates but not those from mouse, rat, or pig. The V gamma 2V delta 2 TCR tetramer also bound to the membrane-associated HMBPP on primary monocytes, B cells and T cells. Consistently, endogenous phosphoantigen produced in Mycobacterium-infected dendritic cells was transported and presented on membrane, and bound stably to the V gamma 2V delta 2 TCR tetramer. The capability of APC to present HMBPP for recognition by V gamma 2V delta 2 TCR was diminished after protease treatment of APC. Thus, our studies elucidated an affinity HMBPP-APC association conferring stable binding to the V gamma 2V delta 2 TCR tetramer and the protease-sensitive nature of phosphoantigen presentation. The findings defined APC presentation of phosphoantigen HMBPP to V gamma 2V delta 2 TCR.