Thy.1lowCD3- cells sorted from nylon wool-passed bone marrow cells can augment the H-2 identical but not non-identical cytotoxic T lymphocyte precursors in mixed lymphocyte cultures.

Thy.1lowCD3- cells obtained from nylon wool-passed murine bone marrow (NW-BM) cells by cell sorting did not express CD4, CD8, or T cell receptor-alpha/beta and -gamma/delta on their cell surfaces. An extremely limited number of B10.BR (H-2k) responder lymph node (LN) cells were stimulated with B10.D2 (H-2d) stimulator spleen cells in cultures containing the minimum required dose of rat T cell growth factor (TCGF). In these cultures, the generation of cytotoxic T lymphocytes (CTL) was very low. B10.BR Thy.1lowCD3- NW-BM cells, added to these cultures, could augment the CTL generation vigorously, but neither B10 (H-2b) nor B10.D2 cells could. When B10 LN cells were used as responder cells in these cultures, B10 Thy.1lowCD3- NW-BM cells could augment the CTL generation, but neither B10.BR nor B10.D2 cells could. Similar findings were obtained when Lyt-2+ cells or Thy.1+L3T4- (CTL precursor) cells sorted from spleen cells were used as responder cells. Both elements, rat-TCGF and Thy.1low CD3- NW-BM cells, were essential for this augmentation of the CTL generation in this culture system because neither one alone could augment generation, and rat-TCGF could be replaced by Thy.1+ Lyt-2- helper T (Th) cells sorted from spleen cells. These findings showed that NW-BM cells could augment CTL precursors in a self-major histocompatibility complex (self-MHC)-antigen restricted manner, and further that both NW-BM cells and Th cells had different and independent functions to induce CTL.