Activation of phosphatidylinositol-3 kinase by ligation of the interleukin-7 receptor on human thymocytes

Interleukin-7 (IL-7) is a glycoprotein that regulates lymphocyte precursor growth and differentiation. However, the exact mechanism whereby the IL-7 receptor (IL-7R) mediates these cell growth signals remains unknown. One of the earliest metabolic events linked to mitogenic responses in other growth factor receptor systems is the activation of phosphatidylinositol-3 kinase (PI-3 kinase). We demonstrate here that ligation of the IL-7R results in dose- and time-dependent increases in PI-3 kinase activity. These results suggest that PI-3 kinase is involved in signal transduction via the IL-7R in human thymocytes.