T-cell growth factors: interleukin 2

One of the key aspects of immunoregulation is the ability of T-cell subpopulations to help or suppress the expression of antigen-sensitive lymphocytes. The cloning of lymphoid cells - usually neoplastic cells - has long been a basic approach to the analysis of cellular function within the immune system but in the investigation of how T-cells act, T-cell lymphoma lines have been of limited value because the antigen specificity of their effector functions could not be detected. Now, however, lymphokines have been isolated which permit the growth of continuous lines of human and mouse T-cells with known specificity for antigen(2-8). In this review, James Watson and his colleagues discuss these lymphokines and some of the outstanding questions about their nature and function.