The role of thymus for the development and prognosis of hypertension and hypertensive vascular disease in mice following renal infarction.

Partial infarction of one kidney and contralateral nephrectomy was followed by a rapid and significant increase in blood pressure both in haired mice with a normal thymus function and in nude mice with genetical aplasia of the thymus. The level of blood pressure and the prognosis were not influenced by the presence of thymus within the first 3 months after partial infarction of the kidney; but a significantly more pronounced increase in blood pressure after 4 months was observed in a small group of haired mice than in a similarly treated small group of nude mice. A marked degree of round cell infiltration around intrarenal arteries was only found in the haired mice, commencing 2 months after partial infarction of the kidney. Degenerative changes were observed in the kidneys of the haired mice 2-4 months after infarction. Very few of these lesions were found in the nude mice. Atempts to transfer the hypertension by means of viable lymph node cells from hypertensive donors to normotensive syngeneic recipients failed. The results support the assumption that high intravascular pressure induces thymus-dependent immune reactions against substances in teh vascular walls which, in turn, may have a prognostic significane; the results give no support for the assumption that the earlier phase of the hypertension which follows partial infarction of the kidney and contralateral nephrectomy is thymus-dependent.