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Evolution led to different natural killer cell receptors in humans and chimps
A new study by Stanford University researchers focuses on an important difference in the immune systems of humans and chimpanzees.
Researchers report in the journal PloS Genetics that while human and chimpanzee immune systems have many similarities, some important differences involve receptors for the white blood cells known as natural killer cells.
The authors said differences between these receptors apparently developed after humans and chimpanzees separated 6 million years ago. The differences may help to explain why humans and chimpanzees are not equally susceptible to devastating infectious diseases such as HIV/AIDS and malaria.
Natural killer cells play a role in immune defense and in reproduction. Selective pressures in human evolution have caused the cell receptors to function differently than they do in chimpanzees. While the receptors are geared toward fighting infection in chimpanzees, they have struck a balance in humans between battling infectious bugs and building babies. Early in human pregnancy, natural killer cells in the uterus help enlarge the maternal arteries that supply blood to the placenta and nourish the fetus.
The following video provides a good overview of the human immune system and the place of natural killer cells in that system. An explanation of natural killer cells begins at about 1:29.