These studies described were designed to determine whether interleukin 2 (IL-2) inhibits lymphocyte migration. The human lymphoblastoid cell line QIMR-WIL was used as an indicator of lymphocyte migration inhibition. Interleukin 2 inhibited QIMR-WIL migration in a dose-dependent manner, high doses of IL-2 (100 units) being strongly inhibitory, and low doses (12.5 units) less inhibitory. Purified natural IL-2 and recombinant IL-2 both inhibited QIMR-WIL migration. The effect of IL-2 on lymphocyte migration was specific. When the IL-2 receptors were blocked with anti-Tac (anti-IL-2 receptor) antibodies, the inhibitory effect of IL-2 was significantly reduced. Similarly antibody to IL-2 blocked the inhibitory effect of IL-2. Lymph node lymphocytes were also used as indicator cells in migration studies and IL-2 inhibited their motility. These data suggest a role for IL-2 in inhibiting lymphocyte migration similar to that of lymphocyte migration inhibition factor produced by antigen- or mitogen-stimulated T lymphocytes. While it is widely recognized that lymphocyte motility can be reduced by lymphocyte migration inhibition factor, these data indicate that IL-2 can also reduce lymphocyte motility.