Posttranslational modification of interleukin-2 is a late event during activation of human T lymphocytes by ionophore A23187 and phorbol ester.

Human peripheral blood lymphocytes secrete high titers of interleukin-2 (IL-2) after stimulation by Ca2+-ionophore A23187/phorbol 12-myristate-13-acetate. During the first 30 hours of incubation cells secrete only the nonglycosylated IL-2 M form of the lymphokine, the glycosylated forms IL-2 N1,2 being detected only after prolonged culture times (30-48 h). After recultivation of cells for a second 48 h period (without additional mitogen), the glycosylated and nonglycosylated IL-2 forms are secreted at a constant ratio of 7:3 throughout. The detection of glycosylated IL-2 is parallelled by an increase in cellular glycosyltransferase activities involved in formation of sialylated oligosaccharides O-linked to proteins.