Many people notice that some lymph nodes in their bodies become swollen when they get sick, because these structures are working overtime to produce more white blood cells to fight the infection. (wisegeekhealth.com)
In an attempt to warm up, the body speeds up its metabolic rate and activates the immune system, releasing more white blood cells. (entrepreneur.com)
The penetrating heat also raises the core body temperature which creates a «false fever» in the body forcing the immune system to spring into action and start making more white blood cells. (infraredsauna.com)