Superoxide and inflammation contribute to the genesis of hypertension but the mechanisms involved are not fully understood. We examined the hypothesis that oxidative stress in dendritic cells (DCs) alters endogenous proteins via Isoketal-modification leading to formation of neo-antigens, T cell activation and blood pressure elevation. DCs isolated from mice with angiotensin II-induced hypertension had a significant increase in NADPH oxidase-dependent superoxide production when compared to sham-treated mice (334.0±49.7 versus 65.8±4.5 pmol/mg protein). This was associated with an exuberant DC accumulation of protein-isoketal adducts and activation of IL-6, IL-1β and IL-23 production. DCs from hypertensive mice but not sham mice promoted survival and proliferation of CD8+ T cells in culture. Scavenging of isoketals not only prevented activation and immunogenicity of DCs, but also markedly attenuated angiotensin II-induced hypertension (142.59 ± 8.98 mmHg versus 175.53 ± 5.19 mmHg in controls). Moreover, adaptive transfer of DCs from hypertensive mice primed development of hypertension in mice given a sub-pressor dose of angiotensin II (157.45 ± 33.86 mmHg versus 119.90 ± 17.33 mmHg in controls). These studies show that angiotensin II-induced hypertension activates DCs, in large part by causing superoxide production and formation of isoketals. We propose that Isoketal-modified proteins can be presented as neo-antigens by DCs, which in turn trigger T cell activation leading to hypertension.