Cellular events in tolerance. VIII. Analysis of the proliferative capacity of antigen-binding cells isolated from normal or tolerant spleens

Previous studies in our laboratory have demonstrated that hapten-binding lymphocytes (ABC) can be isolated from the spleens of mice rendered tolerant to the hapten. These cells are reduced in PFC precursor frequency when stimulated with either specific antigen or mitogen (Reference 6). In the present studies, we have combined antigen-specific cell isolation and an analysis of thymidine uptake by purified B cells to determine whether hapten-binding B cells in tolerant mice can be stimulated to proliferate in response to specific antigen. Compared with normal ABC, 'tolerant' ABC showed a significantly reduced thymidine incorporation responsiveness in vitro. This suggests that unresponsiveness in adult mice can result in an impairment of clonal proliferation. Hence, these 'tolerant' ABC appear to be functionally, though not physically, deleted.