Carl Zimmer in his blog, The Loom:
In March, six men entered a London hospital to receive an experimental drug. The men were volunteers, and the drug–a potential treatment for arthritis and leukemia–appeared from animal tests to be safe. But within minutes of the first round of doses, there was trouble. The men complained of headaches, of intolerable heat and cold. The drug made one man’s limbs turned blue, while another’s head swelled like balloons. Doctors gave them steroids to counteract the side-effect, and managed to save their lives. But several ended up on life support for a time, and they all may suffer lifelong disruptions to their immune systems.
How could such a devastating disaster come from a trial that followed all the rules, including tests on both mice and monkeys? According to a paper published today, the drug developers might have thought twice if they had known more about our evolutionary history.
Humans suffer from a number of immune disorders that don’t bother other primates. HIV evolved from a virus that infects chimpanzees, but when chimpanzees get infected, their immune system doesn’t collapse the way ours does. Chimpanzees don’t get serious inflammation of the liver after hepatitis infecitons, and don’t seem to suffer from lupus or bronchial asthma. All of these disorders are associated with an overreaction by a group of white blood cells known as T cells. This puzzling pattern led scientists at the University of California at San Diego Medical School to see if T cells behave different in humans than in chimpanzees, and if so, why.