TI Studies on the Biological Effects of Ozone: Induction of Tumor Necrosis Factor on Human Leucocytes. DT 1991 AU Luana Paulesu, Enrico Luzzi and Velio Bocci SO Lymphokine and Cytokine Research, Volume 10, Number 5 AB The effect of ozone as a probable inducer of tumor necrosis factor (TNF) has been investigated on human blood and on Ficoll-purified blood mononuclear cells (PBMC). Samples were exposed at different ozone concentrations ranging from 2.2 to 108 ug/ml and incubated at 37 degrees Celsius in an 95% air-5% C02 atmosphere. At predetermined times, all cell supernatants were tested for TNF activity and some PBMC cultures were examined for DNA synthesis. We have shown that ozone concentration is critical in terms of TNF production and of cell mitogenesis and that, owing to the presence of erythrocytes, higher ozone concentrations are required to be effective in blood than in PBMC. Because ozonization of blood is a procedure followed in several European countries for the treatment of viral diseases and tumors, the release of factors with antiviral and immunomodulatory activities by leukocytes may explain the mechanism of action of ozone and of autohemotherapy.