A simple, inexpensive amino acid may play an outsized role in how well the immune system spots cancer and viruses. Researchers at Rockefeller University report in Cell that when arginine runs low, cells can no longer build enough MHC-1 — the protein that displays suspicious proteins to T cells — allowing threats to slip past immune detection.
The mechanism is elegant: MHC-1 is packed with arginine, and when the amino acid is scarce, the ribosomes that assemble proteins literally stall halfway through. The team found arginine was "the most depleted amino acid" across colon cancer, influenza, and SARS-CoV-2 models — and that a moderate dose, roughly the amount in a couple of over-the-counter tablets, restored the genes needed for MHC-1 production.
The dietary results were striking. Mice fed an arginine-rich diet developed fewer colon tumors than those on low-arginine chow, and their flu and COVID infections were milder. Giving mice arginine after a flu infection even improved their outcomes — a result the authors did not expect.
First author Qiushuang Wu noted that arginine levels naturally decline with age, which could help explain why aging and poor nutrition make people more vulnerable to cancer and respiratory viruses. Senior author Sohail Tavazoie said arginine "is inexpensive and readily available," and called for therapeutic and preventative studies — including alongside immunotherapy — "soon."
