Background
T cells bearing the Gamma9/Delta2 T cell receptor (TCR) constitute two to ten percent of peripheral blood T lymphocytes. They have recently raised much interest as non-MHC restricted effector cells against a variety of tumors. Gamma/Delta T cells are known to be stimulated by phosphoantigens without the need of professional antigen presenting cells. Furthermore, it is described that incubation with phosphoantigens increases their proliferation rate rapidly.