DNA acquired from breeding with Neanderthals may explain why people of European descent respond differently to infection than those of African descent, two studies suggest. The findings might also offer insight into why people of African descent are more prone to autoimmune diseases caused by an overactive immune system. In a new study, geneticists of the University of Montreal in Canada collected blood samples from 80 African Americans and 95 people of European descent. From each sample, they isolated a type of immune cell called macrophages, which engulf and destroy bacteria, and grew these cells in a dish. Next, they infected each culture with two types of bacteria and measured how the cells responded. Macrophages from African Americans, they found, killed the bacteria three times faster than those of European Americans. The researchers then measured how gene expression changed in response to the infection. About 30% of the approximately 12,000 genes that they tested were expressed differently between the two groups, even before infection. And many of the genes whose activity changed the most during the immune reaction had sequences that were very similar between Europeans and Neanderthals, but not Africans. http://www.nature.com/news/neanderthal-dna-affects-ethnic-differences-in-immune-response-1.20854
