Chemical sensitivity — including MCS — is obviously a complex illness. However, research —often spurred by the conferences of the Chemical Injury Information Network (CIIN)— leads us away from the belief that the immune system is the culprit in the illness. For sure the immune system can be screwed up, but that is more a symptom of the illlness. In fact, the immune system can react in various ways in MCS. Sometimes it is depressed— sometimes it is hyper activated—and sometimes it remains mostly uninvolved.
When trying supplements or other treatments focused on the immune system, people must be careful to not agrevate the problem by, for example, doing things to boost the immune system when it is already overactive. I've talked to hundreds of people with chemical sensitivities over the past 14 years who have piled on treatments and supplements —usually based on well-intended suggestions— without regard for the specifics of their situation, their symptoms. It can be a wealth-draining waste or it can make a horrible situation worse.