Cremophor EL augments the cytotoxicity of hydrogen peroxide in lymphocytes dissociated from rat thymus glands

Abstract

The pharmaceutical uses of cremophor EL, a non-ionic surfactant, are similar to those of polysorbate 80. In our previous study, polysorbate 80 exerted some adverse actions on rat thymocytes under in vitro condition. Therefore, the effects of cremophor EL on thymic lymphocytes were examined using a flow cytometer with appropriate fluorescent dyes. Cremophor EL at 10 μg/ml or more (up to 300 μg/ml) concentration-dependently decreased cellular content of glutathione. The cell viability of thymocytes under control condition was 95.4 ± 1.2% ( n = 7, mean ± S.D.). The incubation of thymocytes with 300 μg/ml cremophor EL or 3 mM hydrogen peroxide for 2 h, respectively, decreased the cell viability to 90.8 ± 2.8% or 91.2 ± 2.6%. However, the simultaneous incubation with cremophor EL and hydrogen peroxide decreased the cell viability to 28.7 ± 8.2%. Cremophor EL at 100 μg/ml accelerated the process of cell death induced by hydrogen peroxide. Results suggest that cremophor EL increases the susceptibility to oxidative stress. Cremophor EL at clinically relevant concentrations may increase the therapeutic potential of some anticancer agents to produce oxidative stress.