Study: Blood Stem Cells Fight Invaders

U.S. scientists discovered that blood stem cells are capable of identifying and attacking invading pathogens as part of the innate immune response.

The research, led by Harvard Medical School Professor Ulrich von Andrian, overturns the long-held theory that blood stem cells reside primarily in the bone marrow and, for the most part, remain passive.

The new findings suggest blood stem cells’ biological role is far more versatile and dynamic. Von Andrian and his colleagues found hematopoietic stem cells can travel from bone marrow, through the blood system and enter visceral organs where they perform reconnaissance in search of pathogenic invaders.

Upon encountering an invader they immediately synthesize a defense, divide and mature, producing new immune system cells such as dendritic cells and other leukocytes, the researchers said.

This process changes the way we look at blood stem cells, said von Andrian. That stem cells are actually a part of the immune system, rather than just giving rise to it, is a very provocative idea. This opens up a number of new avenues for us to explore ways that our bodies fight pathogens.

The research appears in the Nov. 30 issue of the journal Cell.