We have explored the thymus dependency of T cell precursors in mouse neonatal spleen. Neonatal spleen was grafted under the kidney capsule of adult syngeneic recipients [normal, adult thymectomized (ATx) or thymectomized, irradiated, and bone marrow reconstituted]. Grafts were tested for the presence of Ig+ and Thy 1+ cells and the response to phytomitogens and allogeneic cells. In normal and ATx recipients the grafts were partly populated with Thy 1+ cells of graft origin, which developed in situ from T cell precursors having migrated to the spleen before birth. The absence of the thymus (ATx recipients) did not prevent the appearance of Thy 1+ cells but impaired their functional maturation as assessed by Con A responses and mixed lymphocyte reaction. Such functions appeared to be sensitive to the humoral function of the thymus since they reappeared after grafting of a thymus gland in a cell-impermeable Millipore chamber. No T cell development was observed when neonatal spleens were grafted into T cell-deprived mice, suggesting that T cell precursors that preexisted in the spleen before grafting disappear in T cell-deprived mice whereas they persist in normal or ATx mice. One may thus hypothesize that the persistence and/or proliferation of T cell precursors in the neonatal spleen require the presence of a T cell environment, whereas its functional maturation is under the control of the humoral function of the thymus.

This content is only available via PDF.
You do not currently have access to this content.