Until now, most prion research explored brain tissue--the end point of infection. But a few investigators are seeking the site where prions pathogenesis begins. And their work is converging on a little-mentioned resident of the intestinal lining called an M cell.
M cells link the digestive and immune systems.1 They provide a portal for ingested bacteria and viruses to lymphoid tissue beneath the intestinal lining. "M cells sample antigens so that the body can mount an effective protective immune response," explains Marian Neutra, a professor of pediatrics at Harvard Medical School. But the M cell defense isn't foolproof. "Pathogens have evolved faster than us to exploit this antigen sampling mechanism," she adds. Certain bacteria and viruses usurp the M cell connection, and prions may do so too. Their passage to humans from tainted food-beef in the case of vCJD, and human flesh decades ago in kuru among the Foré people ...
