EVIDENCE FOR A SMALL POOL OF IMMUNOCOMPETENT CELLS IN MOUSE THYMUS

The graft-versus-host reactivity of thymus cells from normal mice was compared with the reactivity of thymus cells from mice previously injected with cortisone or X-irradiated with 400 R. The reactivity of the cortisone-resistant cells was ten times higher than the reactivity of normal thymus cells, whereas X-irradiation did not increase the relative reactivity of the thymus cells. The cortisone-resistant cells, which are known to be located in the thymus medulla, were found to have the same volume distribution as normal lymph node lymphocytes. © 1969.