EFFECT OF NEWBORN AND EMBRYONIC HEMOPOIETIC LIVER CELLS WITtt THYMUS FUNCTION* BY OSIAS STUTMAN, M.D.,$

The ability of thymus to restore the immune deficiency produced by neonatal thymectomy in mice decreases with the delay of treatment after thymectomy (1). Eventually a state is reached when thymus grafts become ineffective, especially when the animals develop the postthymectomy-wasting syndrome (2, 3). These results were interpreted as indicating that a population of cells in the host, capable of responding to the action of thymus, decreased progressively with time in absence of thymus (1). Under these conditions, and using as model the 45-day old, neonatally thymectomized mouse, we have shown that lymphohemopoietic cells of adult and newborn origin can act in cooperation with thymus function in restoring such a host (4). This cooperative effect was observed especially with cells from spleen, lymph node, thoracic duct, thymus, bone marrow, or newborn hemopoietic liver (4). The cooperative effect of the adult or newborn cells was observed whether thymus and thymoma grafts or thymus and thymoma within diffusion chambers were used (4).