Immune System's Double Duty.

The article discusses the hypothesis of Margaret McFall-Ngai that the immune system keeps each species of microbes in the human body in its proper niche and quantity. More biologists are starting to believe that aside from its protective role, the immune system acts as a regulator of the microbial community to maintain communities of bacteria in balance. The hypothesis, if confirmed has a big impact on medicine because many health problems have been linked to imbalances in the bacterial communities, including inflammatory-bowel disease and obesity.