| Abstract: | Bone marrow cells and thymus cells were observed in cell transfer experiments to collaborate in the production of anti-BSA antibodies. The target cells for tolerance induction either with a `low dose' of antigen (100 μg of deaggregated BSA once a week × 5) or with a `high dose' (a single injection of 5000 μg) were identified by the same technique. In `low dose' tolerance, some indication was obtained that thymus-derived cells in peripheral lymphoid systems were the target cells; bone marrow-derived cells appeared not to be so susceptible, and the cells residing in thymus or bone marrow seemed to remain unimpaired. In contrast, the injection of a `high dose' of tolerogen rendered both types of cells in spleen, thymus cells and bone marrow cells, unresponsive or hyporesponsive in parallel with one another. |
