Phosphoantigen

Phosphoantigen refers to a class of small, non-peptidic, pyrophosphate-containing metabolites that can activate human Vγ9Vδ2 T cells, a major γδ T cell subset in circulation[1][2][3][4][5]. These molecules include endogenous metabolites such as isopentenyl diphosphate (IPP) and exogenous microbial metabolites like 3-hydroxy-methyl-but-2-enyl pyrophosphate (HMBPP)[1][4][5]. Phosphoantigens themselves are not protein targets, receptors, or enzymes, but rather small ligands primarily recognized in the context of their binding to the intracellular domain of butyrophilin 3A1 (BTN3A1), which then, by an "inside-out" mechanism, leads to activation of Vγ9Vδ2 T cells involved in immune responses against cancer and infection[1][2][3][4][5]. Medicinally, phosphoantigens have served as lead molecules for the development of immunotherapies and as indirect targets for drugs such as aminobisphosphonates, which modulate their intracellular levels[5]. Notes: - Phosphoantigen is not a receptor, enzyme, or a conventional therapeutic target by itself, but rather a type of small molecule ligand[1][2][3][4][5]. For drug discovery or immunotherapy, the true target would be "Butyrophilin 3A1" (BTN3A1), the protein mediating their recognition by γδ T cells[1][2][3][4]. - Marked "is_incorrect: true" because "Phosphoantigen" is a class of small molecules, not a single protein or drug target, and thus not a proper canonical therapeutic target according to the conventions given.

Other names

pAgdiphosphate metabolitespyrophosphate metabolites

Indirect activation of Vγ9Vδ2 T cells via accumulation or presentation by butyrophilin 3A1