January 14, 2005

New network of immune cells discovered

A previously unknown network of immune cells has been discovered in the mammalian gastrointestinal system by researchers at the MGH Center for the Study of Inflammatory Bowel Diseases. The finding, reported in the Jan. 14 issue of Science, could lead to better understanding of how the immune system recognizes and responds to dangerous bacteria and viruses and to new approaches to immunization and infectious disease treatment. "We found an extensive system of immune cells throughout the intestinal tract that take up bacteria and other antigens, giving us a new target for understanding the immune response," says Hans-Christian Reinecker, MD, of the MGH Gastrointestinal Unit, the study's senior author.

The investigation focused on dendritic cells, which use long extensions called dendrites to continually sample their environment. The cells gather bacteria and viruses and in essence teach other immune cells to destroy the pathogens. Detailed analysis of tissue from mice showed that dendritic cells were much more extensive throughout the gastrointestinal system than previously believed and that they reach intestinal contents by extending dendrites right through the intestinal lining. Cells that could not form normal dendrites were not able to correctly react to either harmless or disease-causing bacteria.

"Insights into these mechanisms could lead to better understanding of conditions such as Crohn's disease and ulcerative colitis, intestinal infections and food allergy, and targeting these dendritic cells could help us develop new types of vaccines," says Reinecker.

The study's MGH co-authors are first author Jan Hendrik Niess, MD; and Stephan Brand, MD; Xiubin Gu; Beth McCormick, PhD; and Jatin Vyas, MD, PhD.