International Association Against Painful Experiments on Animals

101 Misleading results from Vivisection Animal Experiments

55: Steroids & the Immune System

Because of their potent effects on the immune system, corticosteroid drugs are widely used in medicine. They also have many side-effects which limit their usefulness, and much research has been carried out to discover exactly how the drugs work. However, there are said to be “remarkable differences in susceptibility to glucocorticosteroids between various species,” with animals being classiffed as steroid resistant or steroid-sensitive.(1) In mice, a steroid-sensitive species, a single dose of cortisone produces a 90% decrease in the thymus, an organ that plays a crucial role in immunity. By contrast, the same dose of cortisone given every day for a week, produced only a 37% decrease in the steroid-resistant guinea pig's thymus. And while steroids inhibit the production of circulating antibodies in sensitive animals, the same effect is difficult to achieve in resistant species.(1)

Most of the research on corticosteroids has been carried out on steroid sensitive species such as rats, mice, rabbits and hamsters whereas human beings are steroid resistant.(1)As researchers at the University of Dundee point out “The mode of action of these drugs is very complicated, so it is regrettable that most of the extensive literature on animal experimental work is irrelevant to human therapeutics since many species respond in a very different manner from man.”(2) Consequently they concentrated on human clinical studies and test-tube experiments.


1) H.N.Claman, New England Journal of Medicine, 1972, August 24, 388-397.
2) J.S.Beck & M.C.K.Browning, Journal of the Royal Society of Medicine, 1983, vol. 76, 473-479.

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