Antigenic stimulation regulates the expression of IL 2 receptors in a cytolytic T lymphocyte clone

We have isolated and characterized an H-2Kb-specific CTL clone, B1.8, whose growth is strictly dependent on IL 2 and periodic exposure to stimulator cells. A single, brief encounter with antigen induces on resting B1.8 cells the expression of high-affinity IL 2 receptors, which is maintained for several days, thus allowing cells to undergo at least six rounds of division in the presence of affinity-purified IL 2. We show with the use of monoclonal anti-Lyt-2 or -H-2Kb antibodies, which block specific antigen recognition by B1.8 cells, that continuous antigenic stimulation is not required during this period of growth. After this time, B1.8 cells lose their ability to respond to IL 2 and revert to a resting state, a process that is reversed upon addition of fresh stimulator cells. The decline and subsequent arrest of cell growth correlates with a loss of IL 2 receptors; growth-arrested cells express a 10-fold lower number of receptors than actively growing cells.