Functional maturation difference between splenocytes that form autologous rosettes in adult thymectomized and aged...

Thymic hormones induce changes in surface markers and functions in precursors of T cells during maturation. In previous studies, thymopoietin32-36 (TP-5) was found to influence maturation of immature splenocytes characterized by their ability to form autologous rosettes (A-RFC) and bind peanut agglutinin (PNA). These immature cells were increased in numbers in the spleen of nu/nu mice, adult thymectomized animals (ATx) and aged mice, which lack thymic factor activity in serum. Following in vitro exposure to TP-5, reduction in the number of A-RFC and splenocytes bearing receptors for PNA was observed while a small number of cells, which did not possess Thy-1.2 antigen originally, acquired this phenotype. However, it remained to be determined whether these surface changes were equivalent to T-cell differentiation. The present study was undertaken to clarify whether changes in surface receptors influenced by thymic hormones in vitro are associated with changes in cellular functional activities. Under the influence of facteur thymique sérique (FTS), maturation of isolated populations of immature splenocytes (A-RFC+) from ATx mice and aged animals was accompanied by loss in ability to form autologous rosettes but acquisition of a functional activity was observed only in splenocytes from ATx mice and not in those from aged mice.