Origins of Immune Gene in Humans Inherited from Neanderthals

A human's immune system is crucial to recognizing and defeating dangerous invaders. Now, scientists have discovered a little bit more about the origins of our immune system. It turns out that the blueprint for this advantageous structure was first located in the genome of Neanderthals, which hints that humans may have inherited it from these ancient hominids.

When pathogens infect the human body, the immune system first identifies and then attacks the invaders. During the process of human evolution, an efficient defense system developed to protect the body against foreign invaders. The human leukocyte antigen system (HLA) produces receptors that assess the risk rate of the pathogens using their profile which has just eight amino acids.

The immune system breaks down the invader proteins into peptides and then scans a portion of them for their amino acid sequences. Up until now, a total of three different peptide receptors of more than 1,000 different manifestations were known that could read the telltale letter combinations. This variety in particular is needed so that the immune system can rate the entire spectrum of pathogens that are relevant to humans. Now, researchers have discovered a fourth receptor, abbreviated as "HLA-DRaDPb."

This new fourth receptor consists of the combinations of subunits of already known receptors. The scientists found that an estimated two-thirds of Europeans carry this important structure, yet this structure is rare in people in southern Africa.

"When early man, the ancestor of today's humans, left Africa and migrated a few hundred thousand years ago to Europe, he did not yet have this receptor," said Norbert Koch, one of the researchers, in a news release.

After investigating a bit further, the researchers discovered that Neanderthals had the key sequence which contained the blueprint for the receptor. In fact, the identified Neanderthal gene sequence was almost identical with that of modern humans. This suggests that modern humans owe this advantageous receptor to the Neanderthals.

The findings are published in the Journal of Biologial Chemistry.