Development of cytotoxic T lymphocyte precursor cells in T cell colonies grown in vitro

T cell colonies grown in vitro from normal mouse spleen cells contain cytotoxic T lymphocyte precursor cells (CLP) that develop from immature precursors within the colonies. The colony-forming unit for CLP development (CFU-TCLP) has two components. One is Thy-1-, Lyt-1-, Lyt-2- and is found in spleen, nude spleen, and bone marrow. It can by itself produce a colony, but these colonies do not contain CLP. The other component is Thy-1+, Lyt-1-, Lyt-2- and is found in spleen and lymph node. The Thy-1+ component gives rise to the CLP that develop in the colony. A single cell in this component can give rise to multiple progeny CLP. Each colony develops CLP of several different specificities. The full repertoire developed includes specificities specific for allogeneic H-2, TNP-modified-self H-2 and TNP-modified-allogeneic H-2. Although CLP specific for TNP-modified-allogeneic stimulator cells are definitely present, there is a distinct preference for TNP-modified self. The results lead to the tentative conclusion that the T cell repertoire can develop in the absence of the special environment provided by the thymus.