Your immune system’s B cells can produce antibodies against an amazing number of pathogens—viruses, bacteria, etc.—without ever having encountered them. That’s because, as they develop, your B cells reshuffle their antibody-producing genes into an amazing number of possible combinations—more than 100 million—to produce what’s called your primary pre-immune B cell repertoire.
It’s long been thought that in people and in mice this reshuffling process—called V(D)J recombination, after the B cells’ antibody-coding V, D and J gene segments—takes place in two places: the bone marrow and the spleen. But new research from a team led by Frederick Alt, PhD, and Duane Wesemann, MD, PhD, suggests that there may be one more place B cells go to undergo recombination: the gut. What’s more, that reshuffling in the gut may be influenced by the microbes that live there.
Some 90 percent of us are exposed to the Epstein-Barr virus (EBV) at some point in our lives. While the immune system’s T cells rapidly clear most EBV-infected B cells, about one in a million infected cells escapes destruction. Within these cells, the virus enters a latent phase, kept in check by the watchful eye of so-called memory T cells.
This uneasy relationship usually holds steady for the rest of our lives, unless something suppresses the immune system – such as infection with HIV or use of anti-rejection drugs after a transplant – and breaks the surveillance. The virus can then reawaken and drive the development of certain B cell cancers.