New research shows how B cells direct T cells to granuloma tissue in the lungs where they can activate macrophages to neutralize TB infections.
More than 10 million people are sickened by tuberculosis (TB) globally each year, resulting in 1.5 million deaths. Yet, as many as two billion people are infected with Mycobaterium tuberculosis, the bacterium that causes tuberculosis, and are otherwise healthy and asymptomatic. Scientists who study TB look at those individuals who can tolerate and contain the infection in hopes of developing better treatments and vaccines.
The key feature of tuberculosis infection in humans is the formation of granulomas, or clusters of immune cells in the lungs that contain the infection. These granulomas contain B cells, all-purpose immune cells that perform a variety of functions, from producing antibodies to regulating the activity of other cells. For years, researchers assumed that these B cells must be performing a specific direct function in the granulomas to control TB infection, but in a new study, scientists from the University of Chicago and Washington University in St. Louis show that these B cells are actually directing reinforcements to help.
In the study, published in Nature Immunology, the team eliminated different expected B cell functions one by one in animal models of TB to narrow down the possibilities for which components prevented progression of disease. Nothing seemed to make a difference, whether removing plasma cells that produce antibodies or knocking out other B cell functions that produce immune signaling molecules.