Ascorbate-mediated stimulation of neutrophil motility and lymphocyte transformation by inhibition of the peroxidase/H2O2/halide system in vitro and in vivo.

Neutrophil migration, postphagocytic hexose-monophosphate shunt activity and myeloperoxidase-mediated iodination of ingested Candida albicans and lymphocyte mitogen-induced transformation were assessed in six normal volunteers before and 1 h after a single intravenous injection of 1 g ascorbate. Increased neutrophil motility was observed which was associated with decreased myeloperoxidase-mediated iodination of C. albicans and a slight increase in hexose-monophosphate shunt activity. Lymphocyte transformation was also increased. Alterations in these activities were related to serum ascorbate levels. To investigate the relationship of ascorbate-mediated increased neutrophil motility and lymphocyte transformation to decreased peroxidase activity neutrophils and lymphocytes from normal individuals were exposed to the horseradish peroxidase/H2O2/sodium iodide system in the presence and absence of ascorbate and tested for migratory and proliferative responses respectively. Exposure to the horseradish peroxidase/H2O2/halide system caused inhibition of neutrophil motility and lymphocyte responsiveness to mitogens. However, inclusion of ascorbate protected both the neutrophils and lymphocytes from the inhibitory effects of the horseradish peroxidase/H2O2/halide system.