[Interleukin 2 (IL-2) and its receptor (IL-2R) in healthy individuals and with various disease states].

IL-2 is a cytokine that plays a central role in immune response. It stimulates cellular as well as humoral reactivity. The effect of IL-2 depends on the interaction with its receptor. Recent reports have documented that high affinity interleukin-2 receptors consist of two distinct IL-2 binding proteins, one being alpha chain (p55) and the other being IL-2 beta chain (p75). Expression of the alpha chain or the beta chain alone allows for low affinity or intermediate affinity IL-2 binding, respectively. Alpha receptor is present on activated cells, beta chain is present on resting cells. Decreased production of IL-2 and decreased expression of IL-2 receptor (IL-2R) after stimulation was found in primary and secondary immune deficiencies. Leukemic cells in adult T cell leukemia and hairy cell leukemia express markedly large numbers of IL-2 receptors. Since IL-2 receptors are present on malignant cells but not on normal resting cells, clinical trials have been initiated in which patients with adult T cell leukemia are treated with monoclonal antibody that binds to IL-2 receptor.