We already know that that muscles are an important part of the immune system, and that branched-chain amino acid arginine is a precursor of nitric oxide (which is antimicrobial). Now researchers are figuring out just how arginine works as part of the immune system, above and beyond nitric oxide production.
Turns out, this amino acid signals immune system cells called macrophages to start doing their thing. (Think of a macrophage as a cellular-sized, disease-chomping pac-man). These guys help to get rid of invading cells and bacteria - and arginine seems to really get macrophages moving. In fact, scientists reported in the August 17th issue of Science Signaling that adding arginine to the diet of malnourished mice improved their immune response. They theorize arginine does this through three different mechanisms: nitric oxide production, cytokine stimulation and macrophage signaling.
