EFFECTS OF SONICATED EOSINOPHILS ON THE IN-VITRO SENSITIVITY OF HUMANLYMPHOMA-CELLS TO GLUCOSE-OXIDASE

We report here that cultured human lymphoma cells in the absence of so nicated eosinophils are sensitive to killing by glucose oxidase (beta- D-glucose:oxygen-oxido reductase; EC 1.1.3.4) at concentrations as low as 0.025 mu g/ml, a level that can be rapidly attained in s.c. tumor implants in mice that receive a single nonlethal injection of enzyme. Multiple clonogenic assays were used to measure the survival of human lymphoma cell lines (H9 and ARH-77) cultured for 14 days in complete R PMI 1640 supplemented with exogenous glucose oxidase (0.025-2.5 mu g/m l) or an immunoconjugate containing glucose oxidase (0.25-25 mu g/ml) in the presence or absence of catalase (10 mu g/ml) or an equal number of sonicated human eosinophils with or without supplemental 100 mu M Br-, I-, or SCN-. In addition, we used an immunoassay to measure the c oncentration of glucose oxidase in s.c. implants of the Sp 2/0 myeloma tumor at 0-30 min after an i.v. injection of 50 mu g of enzyme into 2 1 BALB/c mice. Doses of glucose oxidase as small as 0.025 mu g/ml kill ed more than 3 logs of tumor cells. Catalase completely inhibited, and sonicated human eosinophils partially inhibited, the killing by gluco se oxidase or immunoconjugate, whereas supplemental halides had no eff ect. Glucose oxidase i.v. produced levels >0.04 mu g/g of tumor for 30 min after injection with a peak concentration of 0.079 mu g/g of tumo r within 5 min of injection. These results are important because certa in human lymphomas contain extensive extracellular deposits of eosinop hil peroxidase, thereby making these tumors potentially less susceptib le to killing by otherwise therapeutic doses of glucose oxidase.