Association between disturbances in the immune system and hypertension

For many decades evidence has been accumulating which implicates the immune system in the etiology and pathogenesis of hypertension. There appears to be a strong association between hypertension and immunologic dysfunction in humans and in rats. Patients with severe hypertension have significantly higher levels of serum IgG in comparison with normotensive controls. A positive correlation has been found between serum IgG levels and blood pressure in untreated essential hypertensive patients. In some studies it has been demonstrated that autoantibody levels are higher in both untreated and treated hypertensive patients than in normotensive control subjects. Furthermore, in the spontaneously hypertensive rat (SHR), several indices of immune system function have been shown to be depressed. There is also a significant correlation between immune intervention and antihypertensive effects. Short term administration of anti-rat thymocyte serum results in a significant decrease in the arterial pressure of the SHR. Chronic cyclophosphamide treatment prevents the progression of hypertension and significantly reduces its final level in the adult SHR. Neonatal thymic implants from normotensive donor rats delay the development of hypertension and significantly attenuate the level of the hypertensive state in the SHR. Also, thymectomy at an age of 4 weeks delays the development of hypertension in the SHR. The differences in the antihypertensive effectiveness of a variety of immunological manipulations in the SHR may be the result of their different levels of improvement on the severity of the autoimmune process in these rats.