Lysosomes and pyroninophilia in mononuclear cells in hypertensive arterioles. Studies on the blood, arterioles and regional lymph nodes in experimental angiotensin-hypertension in rats.

In the days following the termination of a five hours experimental angiotensin-hypertension in rats the total number of mononuclear cells of the peripheral blood which reacted positively for acid phosphatase was increased by 20–40 per cent, while the number of those containing more than five acid phosphatase granules increased by 65–155 per cent. This changed content of lysosomes supports the view that mononuclear cells from the blood are cells of importance in the catabolism of products from hypertensively damaged arterioles. In sections of damaged arterioles the mononuclear cells increased their number of acid phosphatase granules during their passage from the luminal side through the media to the adventitia, indicating that their function was phagocytic and catabolic. The regional lymph nodes showed morphological changes: An increment of large pyroninophilic cells in the paracortical areas and in the medulla 2–4 days after the termination of the hypertensive period, and an obliteration of the medulla with pyronine-negative cells with a morphology like lymphocytes 5–6 days after. These findings are much like those to be found in the lymph nodes during a development of delayed hypersensitivity in experimental animals.