Immune system and the risk of overstimulation

Our Immune system is functioning according to a permanent balance between the attack of foreign material and tolerance of it depending upon the risk carried by the foreign material. This is a very subtle interplay between T Helper lymphocytes Th1 and Th2. So you are better to have a well balanced immune system rather than an overstimulated one. A disequilibrium originates sometimes in over inflammation. Lack of usual bacterial contacts, large amounts of W6 PUFAs, autoimmunity are causes of such disequilibrium. Body flora must also be kept in good shape (diversity, avoiding to much impact of hygiene products and antibiotics...) because it is part of the tolerance mechanism.