The Polycation Diethylaminoethyl Dextran Potentiates Thermal Cell Killing

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Abstract
The polycation diethylaminoethyl dextran (DEAE-dextran) causes marked potentiation of the effects of hyperthermia (45°C) on HA-1 Chinese hamster ovary cells. The effects of the polycation appear to be mediated at the cell surface and are largely reversed by removal of DEAE-dextran with the polyanion dextran sulphate. Maximal potentiation is observed when polycation and heat are given simultaneously. The polycation also inhibits the capping of concanavalin-A acceptors when used singly and is additive with heat in inhibiting capping; reduction in con-A capping may indicate decreased mobility of cell surface glycoproteins. The mechanism of heat potentiation by DEAE-dextran is not fully understood. Effects on surface charge and cytoskeleton-membrane interactions may be involved. However, the polycation appears to have promise, both in probing mechanisms of heat killing and as an adjuvant to heat treatment; potentiation occurs at extremely low DEAE-dextran levels, with considerable potentiation at a concentration of 0·4 μm.