"Here was a new insight in cold science: the symptoms are caused not by the virus but by its host — by the body’s inflammatory response. Chemical agents manufactured by our immune system inflame our cells and tissues, causing our nose to run and our throat to swell. The enemy is us.
Indeed, it’s possible to create the full storm of cold symptoms with no cold virus at all, but only a potent cocktail of the so-called inflammatory mediators that the body makes itself — among them, cytokines, kinins, prostaglandins and interleukins, powerful little chemical messengers that cause the blood vessels in the nose to dilate and leak, stimulate the secretion of mucus, activate sneeze and cough reflexes and set off pain in our nerve fibers.
So susceptibility to cold symptoms is not a sign of a weakened immune system, but quite the opposite. And if you’re looking to quell those symptoms, strengthening your immune system may be counterproductive. It could aggravate the symptoms by amplifying the very inflammatory agents that cause them."