Chemical Reduction of Oxidized Human Lymphocytes Inhibits Interleukin 2 Production but not Induction of Interleukin 2 Responsiveness

Treatment with neuraminidase (NA) plus galactose oxidase (GalOxase) does not cause stimulation of human thymocytes. However, stimulation can be achieved by addition of exogenous interleukin 2 (IL-2). The IL-2-induced stimulation was inhibited with anti-Tac antibody, indicating that NA/GalOxase-oxidized cells can serve as inducers of functional IL-2 receptors on IL-2-responding T cells. The induction of IL-2 receptors by the oxidized cells was not inhibited by subsequent reduction with borohydride, since the cells could still be stimulated with IL-2. The presence of IL-2 receptors was also confirmed by flow cytometry using indirect immunofluorescence. Peripheral blood lymphocytes can be stimulated by NA/GalOxase treatment, and the conditioned medium from this treatment can support the growth of an IL-2-dependent line. This stimulation can be inhibited with borohydride and restored with IL-2. The conditioned medium derived from the borohydride-reduced cells cannot support the growth of the IL-2-dependent line, indicating that borohydride inhibits the oxidation-induced IL-2 production. The results suggest that NA/GalOxase-oxidized sites can be modified chemically without losing the potential to induce IL-2 receptors.