Researchers showed that a protein known as H2-DM can keep immune system T cells from erroneously assaulting the body's own tissues. Distinguishing between foreign and native is one of the immune system's most important tasks; failure to make this distinction can lead the immune system to attack the body, causing autoimmune conditions like diabetes, lupus, arthritis and multiple sclerosis.
"This protein may be one of the components that goes awry when the immune system's normal inflammatory processes malfunction, leading some T cells to attack the body," says Scott Lovitch, an M.D./Ph.D. student at Washington University and member of the research team. The work will be published this week in the journal Immunity.
Lovitch works in the laboratories of the study's principal investigator, Emil R. Unanue, M.D., the Edward Mallinckrodt Professor and head of the Department of Pathology and Immunology. Unanue's research team studies a group of T cells known as type B T cells.
"During development, as the body begins building its arsenal of T cells to attack various types of invaders, any T cells that attack the body's own tissues are supposed to be deleted," Lovitch explains. "However, our laboratory determined that some of these self-reactive T cells don't get eradicated. These cells are known as type B T cells."
T cells normally go on the attack when other cells known as antigen-presenting cells supply evidence of a foreign invasion. This evidence takes the form of protein bits on the surface of antigen-presenting cells. Based on its inspection of these protein bits, a T cell will either remain inactive or start multiplying in preparation for an attack.