Abstract
Bone marrow (B) and thymic (T) cells taken from adult mice that had been splenectomized within 24 hr of birth showed an inability to cooperate in the IgM response to sheep red blood cells. The defect in collaborative capacity was apparent in both sets of cells, but appeared to be more pronounced in the T cell population. Splenectomy performed at various neonatal intervals indicated that if removal of the spleen were delayed until 6 days after birth, B and T cells of the adult showed a 60% restoration in cooperation. Replenishment of the synergistic ability after neonatal splenectomy could be achieved by injecting spleen cells immediately after spleen removal or 2 months postsplenectomy.