Table 1 B7/B7 ligand family members and functions

CD28

Resting T cells

CD80 or CD86 on APCs

Lowers TCR threshold

Delivers a co-stimulatory signal

Promotes T-cell proliferation, survival, cytokine production, T cell-dependent B cell functions [2]

CTLA-4/CD152

Resting/activating T cells

Outcompetes CD28 for CD80/CD86 binding

Increased TCR threshold

Delivers a co-inhibitory signal [2]

Upregulates indoleamine 2,3-dioxygenase

CTLA-4^-/- mice develop autoimmunity [2]

PD-1/CD279

T cells, B cells, DCs, monocytes, NK T cells, exhausted cells and Tregs

PD-L1 on APCs, B cells, and T cells. PD-L2/CD273 on APCs. PD-L1/CD274 can also bind to CD80

Delivers an inhibitory signal

Suppresses Bcl-xl [2]

ICOS/CD278

Activated T cells, T follicular helper cells

ICOSL/CD275 on APCs and B cells [2]

Induces proliferation

Propagates germinal center reactions

Upregulates IL-10 production [2]

BTLA/CD272

B cells, DCs, Th1 cells, macrophages

Herpes virus entry mediator [2]

BTLA delivers an inhibitory signal via ITIM and ITSM [2]

B7-H3/CD276

B cells, NK cells, T cells, activated monocytes [2]

Unknown

Co-inhibitory and co-stimulatory functions. Suppress antitumor responses [2]

B7-H4/B7S1/B7x/Vtcn1

APCs, cancer cells, and mRNA expression on nonhematopoietic tissue [2]

Unknown

Reduces cell proliferation and T cell interleukin-2 production [2]

B7-H6

Tumor cells [3]

NKp30

Binds NKp30 on NK cells resulting in interferon gamma and cytotoxic function [2]

VISTA/Dies1/Gi24/PD-1H

Highly expressed on murine myeloid cells. Low expression on T cells [2]

Unknown

Inhibits T-cell proliferation, reduces CD44 and CD69 expression [2]

Increases cell motility [2]