Molecular cloning of cDNA for the human interleukin-2 receptor.

Interleukin-2 (IL-2 or T cell growth factor) is a 14,500 daltons glycoprotein critically involved in the development of a normal human immune response [1, 2J. Recently, cDNA for this lymphokine has been isolated and expressed in both prokaryotic and eukaryotic cells [3-5J. Further, the human IL-2 gene has been cloned, sequenced [6], and localized to chromosome 4. As with other polypeptide hormones, IL-2 exerts its biologic effects through binding to specific high affinity membrane receptors [7]. However, neither IL-2 nor IL-2 receptors are produced by resting T cells [7, 8]. Following exposure to antigen, T cells binding antigen enter a program of cellular activation leading to de novo synthesis and secretion of IL-2 and expression of IL-2 receptors. The interaction of IL-2 with its cellular receptor then triggers cellular proliferation, resulting in the growth and development of helper, suppressor, and cytotoxic T cells. Thus, induction of IL-2 receptor expression is a principal mechanism by which the specificity and magnitude of the human immune response is regulated. While IL-2 receptors are not present in most human leukemic T cell lines, these receptors are uniformly expressed in large numbers in adult T cell