A protein fraction (NHG) from serum of normal humans which is cytotoxic for HeLa cells in culture.

A fraction of the alpha-globulins (NHG) from normal human serum was cytotoxic for mouse L-cells in culture and Meth A tumors in mice. NHG inhibited the growth in vitro of human colon cancer (HT-29), melanoma (RPMI 7931) and a neuroblastoma cell line. Survival of HeLa S-3 cell colonies after 24 h exposure to 25, 50, 75 or 100 micrograms NHG/ml medium was 86%, 77%, 40% and 10%, respectively. Whole human serum or purified serum albumin had no anti-HeLa cell activity. These results confirm the presence of a protein in human serum with antitumor activity. An assay for NHG using HeLa S-3 tumor cells is described.

Selective killing of glucose and oxygen-deprived HeLa cells by hyperthermia.

We previously have reported that glucose deprivation specifically enhance cell killing by hyperthermia in the absence of oxygen. The present studies were carried out to evaluate the interplay of glucose and oxygen on cell killing by hyperthermia (37 to 42 degrees) for up to 4 hr under varying concentrations of glucose (0 to 1 mg/ml) and oxygen (0 to 21%). pH 7.4 was maintained in all trials. In the absence of oxygen, enhanced cell killing at 40 and 42 degrees was seen with glucose concentrations below 0.1 and 0.25 mg/ml of media, respectively. In the absence of glucose, enhanced killing was seen when oxygen concentrations were below 1 and 2% at 40 and 42 degrees, respectively. The radiosensitivity of the cells was influenced only by the oxygen concentration during irradiation and not by glucose. These results indicate that oxygen and glucose are important modifying factors of cell lethality by hyperthermia.