Bacteria Invade Cells, Trigger Immune Response from Within

For years, scientists believed that when bacteria invade the body, they activate an immune response by binding to receptors on the surface of immune cells called macrophages — the body’s front-line defense against infection.

A mouse macrophage (cytoplasm in red, nucleus in blue) infected with bacteria (small blue elongated bacillus).

Now, a U-M research team led by Gabriel Nunez, M.D., the Paul H. de Kruif Professor of Pathology, has found that invading bacteria also can slip inside macrophages and trigger the immune response by activating a protein called cryopyrin found in fluid inside the cell. Cryopyrin is implicated in the development of several inflammatory syndromes characterized by recurrent fever, skin rash and arthritis.

This research gives scientists new targets and pathways for future vaccine development, as well as for drugs designed to block the body’s inflammatory response in rheumatoid arthritis and some other autoimmune diseases.

—Anne Rueter

For an expanded version of the story:
www.med.umich.edu/opm/newspage/2007/microbes.htm