Looking like a melted marble, this is a whole mouse lymph node, an organ of the immune system. Within it are hubs (here seen as dense blobs) – germinal centres – where B cells are constantly trying to optimise their antibodies for binding and killing dangerous invaders. Most B cells won’t make the perfect weapon, but those that do are selected to mass-produce it. The selection process is driven by T follicular (Tfh) cells (the green-stained dots), which identify the pathogen before cherry-picking B cells with the best-suited antibodies. How this happens has not been clear. But scientists have now demonstrated that Tfh cells continually move between different germinal centres within a lymph node. That means B cells are influenced by a range of Tfh cells, which may enhance the diversity of the antibodies they produce and therefore ensure a supply of target-specific weapons to tackle an ever-changing cast of intruders.
Written by Daniel Cossins
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