The possibility that lymphokines affect other hormone dependent tumors, particularly tumor cells from the pituitary is the focus to this study. AtT-20 is a mouse tumor cell line that secret ACTH and we have seen that the growth of these cells and the secretion of ACTH is affected by both IL-1 and IL-2. When tumor cell growth is inhibited, ACTH secretion per cell is increased. Conversely, when tumor cell growth is increased ACTH secretion per cell is diminished.