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.