Table 1.

Some important interactions of T lymphocyte surface proteins with tumor cell surface proteins

T lymphocyte surface protein	Tumor cell surface protein with which this T lymphocyte protein interacts	Effect of this interaction on the T cell	Comment
T cell receptor	MHC	Stimulation	First step in the activation of T cells to effector T cells
CD28	B 7.1 and B 7.2	Co-stimulation	Second step in the activation of T cells to effector T cells
CTLA4 (Cytotoxic T lymphocyte antigen 4)	B 7.1 and B 7.2	Prevention of co-stimulation (by blocking the B 7 proteins from interacting with CD28 proteins)	CTLA4 is the target for Ipilimumab, which blocks CTLA4 and thus allows the uninhibited interaction of CD28 with B 7 molecules leading to co-stimulation of T cells
PD-1 (Programmed death-1)	PD-L1 (Programmed death-ligand 1)	Inactivation	PD-1 and PD-L1 are targets for check point inhibitors which prevent the interaction of PD-1 with PD-L1 and thus prevent the inactivation of T cells

Notes: Data from Preusser et al.¹⁷