Thymic Control of Cellular Differentiation in the Immunological System

Publisher Website
Google Scholar
Abstract
Thymectomized and intact (non-thymectomized) adult mice were heavily irradiated and given isogeneic bone marrow. In contrast to the intact mice, thymectomized mice failed to recover the capacity to produce normal numbers of plaque-forming cells after antigenic challenge. However, when cell-impermeable diffusion chambers containing thymus were implanted into thymectomized mice, these animals produced significantly larger numbers of plaque-forming cells than did control mice bearing empty diffusion chambers or chambers containing lymph node or spleen. Since the thymus does not influence the differentiation of antigen-sensitive cells into plaque-forming cells, these results indicate that the influence of the thymus is directed at the differentiation of antigen-insensitive precursors in bone marrow to antigen-sensitive cells. The capacity of thymectomized mice bearing thymus-filled diffusion chambers to produce plaque-forming cells indicates that the thymic influence is mediated by a humoral factor.