Induction and abrogation of unresponsiveness in nude mouse cells.

Nude mice were injected with antigen and T cells at different times to induce unresponsiveness to SRBC. Spleen cells derived from these mice were tested in vitro for the capability to produce antibody-forming cells against sheep erythrocytes in the presence of a T-cell-replacing factor. It was found that priming with antigen alone did not result in paralysis but a later injection of thymus-derived lymphocytes together with antigen results in unresponsiveness of these cells in vitro, provided there was an interval of several days between the in vivo administration of thymus lymphocytes and the explantations of cells to in vitro cultures.