Colony formation of cytolytic T cells in semisolid medium

Addition of supernatant from concanavalin A-stimulated spleen cells to in vitro primed cytolytic T lymphocytes in semisolid medium stimulated the growth of colonies of cytolytic lymphocytes. Optimal results were obtained using a peritoneal adherent cell underlayer where a 10% plating efficiency (greater than or equal to 4 cells per colony) was achieved when between 5000 and 100 000 cells were plated per dish. Individual colonies were harvested and tested in a short term (5h) 51Cr release microassay, employing 200 target cells. The frequency of lytic colonies varied from 46--67%. The observed lytic activities were specific for the relevant allogeneic target cells.