Origin of PHA-responsive Cells in the Mouse Thymus after Treatment of the Animal with Hydrocortisone

AFTER treatment of mice with corticosteroids, the number of cells in the thymus is greatly reduced. However, on a cell to cell basis, these cells are more competent to cause graft versus host reactions and to cooperate with ? cells in antibody responses, than are thymus cells from normal animals^1–6. We are primarily concerned here with the origin of the corticosteroid resistant cells.