Restoration of suppressor function in athymic mice.

Antibody responses of normal and congenitally athymic (nu/nu) mice were measured to the phosphorylcholine determinant of a pneumococcal C-polysaccharide. The plaque-forming cell responses of athymic mice were approximately tenfold higher than for intact controls. This enhancement was equivalent to that obtained by treatment of controls with antithymocyte serum. In both cases, the enhanced responses presumably result from a lack of suppressor T cells. Reconstitution of athymic mice with normal thymocytes restored both suppressor and helper T cell functions. Whereas suppressor activity did not appear until 6 days after transplantation of T cells, helper activity was fully restored within 24 h and had diminished by 6 days.