Expansion strategies for Vδ2 γδT cells in cancer immunotherapy: Activation, cytokines, and culture conditions

Table 2 Selected phosphoantigens used for in vitro activation or expansion of Vδ2 cells

Abbrev name	Full name	Relative strength	Source	Stability in aqueous solution	Ref.
IPP	Isopentenyl pyrophosphate	Approximately 1000 × weaker than HMBPP	Eucaryotic cells	Stable	Latha et al[63], Vantourout et al[64]
HMBPP	(E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate	Most potent	Prokaryotic cells	Not very stable	Kilcollins et al[65]
BrHPP	Bromohydrin pyrophosphate	Stronger than isopentenyl pyrophosphate, weaker than HMBPP	Synthetic	Stable	Sicard et al[66]
MEP	Monoethyl phosphate	Unknown	Prokaryotic cells	Stable	Tanaka et al[67]

HMBPP: (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate.