T cells are the foot soldiers of our immune system, deployed on an endless tour of duty around our bodies destroying rogue cells and intruders. They are made in a two-step process that starts in our bone marrow and finishes in a small gland above our heart – the thymus – where they mature into battle-ready cells with specialised skills. It was thought that T cells (here dyed red) matured by a complicated sequence of chemical signals. However, recent findings demonstrate that only four proteins are required. Researchers discovered this by manipulating the chemical environment of a mouse embryo thymus (dyed blue and green), flicking genes on and off like light switches. The discovery prompts a paradigm shift, which could boost research into new drugs. Novel treatments could help rekindle immunity after cancer therapy, and even lead to the creation of artificial thymus glands.
Written by Tristan Farrow
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