Protein matchmaker between immune cells identified

Washington, Oct 11 : A protein that plays matchmaker between two key types of white blood cells, T and B cells, enabling them to establish long-lasting immunity after an infection, has been identified.

This finding may also explain why some individuals who have a genetic defect that prevents them from making this protein - called SAP - suffer from lethal infections with a common virus that otherwise is rarely fatal (Epstein-Barr virus), while others with this genetic defect have problems with B-cell lymphomas.

The new study was a collaboration between the labs of National Institutes of Health (NIH) scientists Ronald Germain, at the National Institute of Allergy and Infectious Diseases (NIAID), and Pamela Schwartzberg at the National Human Genome Research Institute (NHGRI).

When a B cell encounters a virus or other foreign agent, it engulfs the virus and parts of it, called antigens, become displayed on the surface of the B cell. These antigens signal to T cells, which have specialised receptors that can bind to antigens on the B cells, according to a NIAID press release.

Thus coupled, the T cells deliver signals that help B cells multiply and produce antibodies that will eventually destroy the offending virus. A critical tissue structure that facilitates these events is the germinal centre, which normally forms after an infection within the lymph nodes, organs in which immune cells gather to carry out their functions.

"Understanding how B and T cells interact in the lymph nodes is crucial, because the germinal centres are the sites where long-lasting immunity begins," said NIAID director Anthony S. Fauci. "If we can unravel how the body naturally builds defences against repeat infections, it will aid us in developing more effective vaccines."

These findings appeared in Thursday's issue of Nature.