B7-H4 is a B7 family member that negatively regulates T cell immunity by inhibiting T cell proliferation, cytokine production and cell cycle progression. In vitro, B7-H4 inhibits CD4+ and CD8+ T cell proliferation, cytokine production and generation of alloreactive cytotoxic T cells (CTLs). In vivo, blockade of endogenous B7-H4 by specific monoclonal antibody promotes T cell responses. B7-H4 ia an important negative regulator of innate immunity through growth inhibition of neutrophils. B7-H4 is expressed on some tumor cancer cells. The role of B7-H4 in tumor progression may be to transform precancerous cells and then protect them from immunosurveillance.
