This happy face belongs to a giant cell, formed when several immune cells (known as macrophages) team up and fuse together. Although they may look like eyes and a mouth, the dark spots are actually the cells' nuclei – the 'control centres' containing their DNA. These unusual cells are created in certain illnesses where the immune system runs out of control and causes inflammation such as arthritis, which affects the joints, or the kidney disease glomerulonephritis. A molecule on the surface of macrophages, called KCNN4, directs this biological get-together in mice and humans by orchestrating a complex interacting network of cellular signals. KCNN4 has previously been implicated in other types of over-enthusiastic immune response, and drugs that block it are already being tested in clinical trials for immune system-related conditions such as inflammatory bowel disease and asthma. So maybe they could be useful for treating other illnesses too.
Written by Kat Arney
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