20α-Hydroxysteroid Dehydrogenase (20αSDH) — A New Enzymatic Marker for Pre T and T Lymphocytes

Abstract

The enzyme 20αSDH which reduces progesterone to 20α-hydroxyprogesterone is found in various lymphatic organs (1,2), The following evidence suggests that within the mouse lymphocyte population, 20αSDH is confined to T lymphocytes (1,2): 20αSDH activity is found in thymocytes, splenocytes and lymph node lymphocytes from all the normal mouse strains, but not in splenocytes from congenitally athymic or neonatally thymectomized mice; it is associated with spleen cells bearing the ѳ antigen; T-cell mitogens such as Con A and PHA, alloantigens (3), but not the B cell mitogen LPS, are able to induce in vitro an increase in 20αSDH activity (2). 20αSDH is found in thymocytes and T cells from all mouse strains. In the thymus, the 20αSDH activity is located within the hydrocortisone resistant, PNA negative, medullary cells (2,4,5).