The Effect of Oxidant Injury on the Lymphoblastic Transformation of Human Lymphocytes*

We have studied the effect of oxidant injury on the lymphoblastic transformation and glucose metabolism of human lymphocytes. Lymphocyte cultures were incubated with xanthine oxidase and xanthine, an enzyme system known to generate several highly reactive oxygen compounds. Lymphoblastic transformation to phytohemagglutinin was quantitated by the stimulation of DNA synthesis as indicated by the 3H‐thymidine uptake of the cultures at 3 days. The lymphoblastic transformation of cultures incubated with the enzyme system was significantly impaired compared to controls. These cultures also failed to demonstrate the burst of glucose metabolism characteristic of transforming cells. To firmly establish that the effect of the enzyme system on lymphoblastic transformation was related to reactive oxygen molecules, the effect of several scavengers was studied. Cultures supplemented with catalase were almost completely protected against the effect of the enzyme system. In contrast, cultures supplemented with superoxide dismutase, mannitol and azide. scavengers of superoxide, hydroxyl radicals, and singlet oxygen, respectively, were not protected. These data indicate that the functional capacity of human lymphocytes can be impaired in vitro by exposure to hydrogen peroxide.