Diabetes mellitus in the rat: diminution in the number of cells in the thymus and of lymphocytes in the blood.

In diabetic rats there is a rapid fall in the weight of the thymus with a great loss in the numbers of thymocytes. In this paper we show that there is also a marked diminution in the number of lymphocytes in the peripheral blood, although the numbers of neutrophils and monocytes are not affected. Since the thymus is thought to be the site in which T-lymphocytes develop, it is suggested that the paucity of lymphocytes in the peripheral circulation reflects the loss of cells from the thymus. The diminution in the number of circulating lymphocytes in diabetes may account for the liability of diabetics to suffer severely from infections.