Induction and long‐term maintenance of Thy‐1 positive T lymphocytes: Derivation from continuous bone marrow cultures

Abstract

In the present study we investigated the presence of T‐lymphocyte progenitors in the long‐term murine bone marrow culture system described by Dexter: mature Thy‐1 antigen‐bearing T lymphocytes are lost in these cultures after a few days. By culturing nonadherent cells from such cultures in the presence of a supernatant of concanavalin A‐stimulated spleen cells, a source of T‐cell growth factor, we found that Thy‐1 positive blast cells proliferated together with a second population of Thy‐1 negative cells. These two populations of cells have been maintained in long‐term in vitro cultures by passaging the cells in fresh conditioned medium at regular intervals. Moreover, we have been able to establish pure cultures of the Thy‐1‐bearing blast cells after separating them from the non‐T cells using their adherence property to plastic surfaces. Long‐term cultures of T lymphocytes can thus be established from long‐term marrow cultures as well as from the spleen, thymus or fresh bone marrow.