CD4 and Hypertension: Circulating CD4+ T cells from hypertensive patients produced more IFN-γ than cells from normotensive subjects, while in mice the inhibition of the B7/CD28 costimulatory axis with CTLA-4–Ig (cytotoxic T lymphocyte–associated protein 4, also called CD152) attenuated Ang II–induced hypertension and T cell accumulation in the aorta (10, 11).