Immunity, smell linked

Peptides that bind major histocompatibility complex (MHC) class I molecules act as chemosensory signals in a region of the brain thought to be important in chemosensory communication, according to a study published in this week's Science. The peptides also acted as individuality signals in behavioral experiments.

"For many years, it has been suggested that there is a functional link between the immune system and the sense of smell," coauthor Frank Zufall of the University of Maryland told The Scientist. "These peptides are the first molecules to provide that link."

MHC molecules are well known for their role in binding foreign peptides and exposing them on cell surfaces for recognition by the immune system, but MHC peptide complexes can also be released into the extracellular space, reach the bodily fluids, and pass to other animals. Because MHC molecules and the peptides that bind them are quite unique for each individual, these ...