[Current knowledge of characteristics and effects of alpha and beta tumor necrosis factors (cachectins)]

The tumour necrosis factors (TNF) alpha and beta play a role in the activation of the immune system in bacterial and viral infections as well as in parasitoses and inflammatory processes, respectively. The TNF alpha is formed mainly by activated macrophages and mast cells, the TNF beta is formed by activated T- and B-lymphocytes. The evocation of necroses in certain forms of tumours is done by the furthering of the formation of activated O2-molecules (H2O2, peroxide anions, hydroxyl radicals). In tumour cells with a high activity of glutathione-peroxidase and of Mn peroxide-dismutase the TNF are without any effect. The TNF activate neutrophil and eosinophil granulocytes as well as macrophages. By induction of the formation of an oligoadenylate synthetase in virus-infected cells they inhibit the virus reproduction. In chronic infections and parasitoses they evoke a retrogression of the fatty tissue (cachexia). The division of fibroblasts is stimulated via the activation of the genes c-myc and c-fos. In the same way like interleukin 1 and interferon gamma they cause fever.