RESUMEN
The increased uptake of hexose by mammalian cells is considered to be a general response to stress. Nowadays, mistletoe lectin separated from the extracts of the European mistletoe (Viscum album L.) is often used in adjuvant cancer therapy. The present work studies the effect of the lectin on unirradiated and x-irradiated tumour cells. The response of cultured human lung carcinoma cells (Calu-1) was followed by radioactive glucose uptake as well as by tritiated thymidine incorporation. The cells were maintained either in a complete or a so-called restrictive medium. Slight metabolic changes were found in the restrictive medium but not in the complete one. Mistletoe lectin I at a very low concentration (0.001 ng/mL) increased the glucose uptake and thymidine incorporation. Ionizing radiation (1 Gy) did not influence the hexose uptake but it enhanced the incorporation of thymidine. It seems that the actions of two different factors (mistletoe lectin I and radiation) proved to be rather provoking stress effects for the tumour cells as detected in the restrictive medium.