Could TH1 and TH2 diseases coexist?
This is a concept that can shake many of our foundations. TH1 immune response is the “killer attack dog” system, while the TH2 is the “killer guard dog” system. TH2 keeps things (bacteria, viruses…) out while TH1 destroys them if they manage to get through. Too much TH1 leads to autoimmune prevalence; too much TH2 leads to allergies and asthma as the immune system overreacts to things trying to get in. Much current thinking does not allow imbalances in the TH1/2 response to coexist–it’s an either or response. However, this concept is beginning to be shattered. We already know that as we age our immune system is less responsive, and yet incidence of autoimmune antibodies increases as we get older. This seems paradoxical, and yet it indicates a dis-regulation in the immune response. The presence of both TH1 and TH2 over-response coexisting is still a new concept and keep yourself open for future theory and research.
Journal of Allergy and Clinical Immunology Online