The role of central memory CD8 T cells in the kidney and the role of these cells in genesis of hypertension

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Immunological memory is an important function of the adaptive immunity in response to pathogenic stimuli. Effector memory T cells, which are CD44 high CD62L low, reside in various non‐lymphoid tissues and serve as a first line defense against foreign antigens. We have previously shown that T cells are important in hypertension, but the role of memory T cells has not been defined. Here, we show that hypertension also causes immunological memory. The presences of CD8+/ CD62Lhi/CC44hi, CCR7hi central memory‐like cells in the kidney are increased 5 to 10‐fold compared to sham infused mice. Moreover, the central memory CD8 T cells produce IFN‐r and up‐regulate IL‐18R. To examine a potential role of these cells in hypertension, we re‐infused a low dose of angiotensin II that minimally raises blood pressure in naïve mice (200 ng/kg/min) 4 weeks after stopping an initial infusion of either high dose angiotensin II or vehicle. This low‐dose angiotensin II increased blood pressure to 137±6mmHg in the animals that had previously received a vehicle infusion, but to 172±12mmHg in mice that had received angiotensin II. Thus, these studies show that hypertension is associated with the development of central memory CD8+ T cells and that these cells may promote a severe hypertensive response to subsequent exposure to angiotensin II. This memory model allows us to investigate the role of memory CD8 T cells in genesis of hypertension.