Th1 and TH2 are polarised responses by the body’s T-helper cells when faced by pathogens. Both should be fully-functioning, but in the case of autoimmune diseases and severe allergies, one or other type of response has gained control of the system.
This is important, because if a disease is identified more closely with one path than other, it gives the physician – and patient – more clues as to how it may be cured. The Marshall Protocol, for instance, which claims to cure autoimmune diseases such as sarcoidosis and Hashimoto's, can only be used on TH1-type diseases.
What are TH1 and Th2?
T-lymphocytes are part of the body’s immune system; they recognise pathogens (foreign bacteria) and they produce cytokines – hormonal messengers that are responsible for biological effects in the immune system. The cytokines fall into two groups: those that are pro-inflammatory, and those that are anti-inflammatory.
The helper T-cells (a type of T-lymphocyte) produce enormous amounts of two types of cytokines: Th1 and Th2. The Th1 cytokines produced by the helper T-cells produce a pro-inflammatory response; The TH2 cytokines produce an anti-inflammatory response, but promote allergic responses.
What Do the TH1 Cytokines Do?
The Th1-type cytokines produce inflammation to kill intracellular parasites (viruses and certain bacteria, such as Listeria and Mycobacterium tuberculosis – the bacillus that causes TB). These cytokines also perpetuate any form of autoimmune response, and can cause cell-mediated allergies.
Th1-type lymphokines are involved in the development of organ-specific autoimmune diseases, such as autoimmune uveitis, allergic encephalomyelitis, or insulin-dependent diabetes mellitus.
What Do the TH2 Cytokines Do?
The TH2 cytokines counteract the effects of the TH1 cytokines – they have an anti-inflammatory action. But they also help kill extracellular pathogens (which live outside the body’s cells and are exposed to antibodies in blood and other body fluids).
The TH2 cytokines induce a pronounced allergic response. If you suffer from IgE-mediated allergies, or asthma, you are likely to be over-producing TH2-types of cytokines, and have a TH2-weighted imbalance.
Th2-cell predominance is found in patients with chronic graft-versus host disease, progressive systemic sclerosis, systemic lupus erythematosus, and allergic diseases.
A Newly-discovered Third Set
A new set of T-helper cells has been identified: the TH17 cells. These are found where the body’s internal and external environments interact, such as the skin and the lining of the intestinal tract. They attack bacteria on those surface, but with accompanying inflammation. TH17 cells are thought to be implcated in: #Crohn's disease (an inflammation of the small intestine); ulcerative colitis (inflammation of the large intestine);
and psoriasis (inflammation of the skin). Mice have also shown signs of TH17 in cases of multiple sclerosis.
Redressing the balance
In a well-functioning immune system, TH1 and TH2 cytokines are both produced by the helper T-cells, and work together to keep everything in balance.
Researchers working on allergies are looking at ways to drive up the TH1 response – to rebalance the system away from leaning heavily into a TH2 response by redirecting the body into using the TH1 cytokines instead. Likewise, researchers working with diseases where the TH1 response is driving the system, are looking at using high-dose exposure to allergens to ‘kick-start’ the TH2 immune response, and rebalance the system.
There is evidence that autoimmune diseases such as multiple sclerosis, type 1 insulin-dependent diabetes mellitus, and posterior uveitis are Th1 mediated – and that in some cases, the diseases can be alleviated by a reduction of the Th1 response or a shift towards Th2 response. But there are exceptions, and some researchers see the Th1/Th2 concept as an integral part of the complex interactions occurring as autoimmune disease develops.
Read more:
Can Antibiotics Cure Hashimoto's Disease?
Autoimmune Disease and the Vitamin D connection
Sarah Tomley - Sarah is an editor and writer who has been working in the UK publishing industry for over 18 years. She has an honours degree in ...
