Autoimmunity and TH1, TH2 Cells
The immune system is comprised of many different parts, all of which play one or more roles in normal and abnormal immune responses. Some of these parts are cells, while others are proteins, messengers or even protein fragments. Today we will look specifically at two of the many cell types involved in immunity and autoimmunity.
What are TH1 and TH2 cells?
“TH” cells are known as T-helper cells, which are a vital part of the body’s immune system, identified by a specific surface protein called “CD4”. They are divided into subgroups 1 and 2, depending on their mechanisms of action, with TH1 cells involved in “cell-mediated” immunity (mostly against viruses and parasites) and TH2 cells directing “antibody-mediated” immunity (mostly against bacteria and allergens).
These helper cells act by producing hormone messenger proteins known as “cytokines”, which serve to initiate one or both pathways against foreign invaders. However, in autoimmune disease, TH cellular responses can be mistakenly directed towards one’s own cells and tissues, sparking unnecessary immune reactions, such as that seen in Hashimoto’s or Lupus.
TH1 cytokine production tends to be pro-inflammatory, normally active during infections or cancers, and leads to many autoimmune conditions and symptoms. On the other hand, TH2 cytokines are more often involved in allergic-type immune reactions (especially of the skin) and generally considered to be anti-inflammatory in effect.
Can understanding whether your body’s dominant response is TH1 or TH2 help you treat your autoimmune condition?
Yes and no. Despite many advances over the past twenty years in identifying cells and proteins involved in autoimmune processes, we still do not fully understand the exact causes or triggers for such reactions. As a result, it is often difficult to treat these conditions, even when indicators such as TH1 and TH2 levels are demonstrated to be out of balance. In addition, the medical community is divided over whether achieving this balance is really a key part of restoring and maintaining health in the face of autoimmune disease.
Having said this, many researchers do believe that such a balance is key to the proper functioning of the immune system, and thus an avoidance of major autoimmune issues and flares. It is thought that an overactive TH1 system needs to be balanced by stimulating the TH2 pathway, and vice versa. Since the former is involved mainly in cellular infections, one approach involves increasing TH2 levels via deliberate allergic stimuli. Conversely, down-regulating the TH2 response might possibly involve intentional infection (as with vaccines) with microbes in order to increase TH1 response and therefore restore balance. Clearly, such practices need to be undertaken carefully and only after consideration of all clinical factors.
For those clinicians who subscribe to these notions, nutrition plays a key role, and several ingestible substances are commonly recommended and have been implicated in the TH1/TH2 balance. These include plant phenols and sterols, melatonin, progesterone, selenium, zinc and certain probiotics, among others. Consultation with your doctor and possibly a nutritionist or herbalist may be necessary to determine which are best for your condition.
What other parts of the immune system are involved with triggering autoimmune responses?
The body’s immune system is a vast and complex web of differently interacting cells, proteins and other molecules, containing many separate components. Without getting too detailed, some of these contributing parts include B and T cells (of which there are several subtypes), an auxiliary “complement” system, antibodies / immunoglobulins (produced by B cells), a variety of other cell types responsible for killing and removal of pathogens, and of course the antigens (from foreign invaders or one’s own tissues) that spark both normal and abnormal (autoimmune) reactions.
There are many postulated mechanisms for how autoimmunity arises, and these differ somewhat depending on the tissues and organs involved. In general it is thought that many autoimmune conditions are initiated by a cross-reaction, whereby a proper immune response aimed at a specific virus or bacteria then begins to attack similar cells native to the human body, mistaking them for invaders. But there are also many cases where reactions to medications or others mechanisms have been implicated, and the specific components responsible for triggering autoimmunity will depend on the condition being considered.
Questions for your doctor:
- Are there any special nutritional requirements to help manage my autoimmune conditions? Specifically, which foods/herbs should I add to or avoid in my diet?
- How do you / we determine whether to treat only the symptoms of disease versus the entire immune system, with immunosuppressants?
- If immunosuppressants are necessary, what are the potential complications and/or precautions?
- What are your personal thoughts on TH1/TH2 balance in terms of autoimmunity? Can you provide any articles/evidence to support your feelings or beliefs?
- For skin problems, if it is probably a result of a TH2 / allergic reaction, will antihistamines and other standard allergy treatments be effective?
About the Author
Dr. Rothbard is a professional medical writer and consultant based in New York City, specializing in medical education articles targeted at a variety of audiences, from children through clinicians. After leaving medicine, he worked as a biology and medical science educator for several years, before deciding to pursue writing full-time. He may be reached at firstname.lastname@example.org.
This blog post was originally published by AutoimmuneMom.com, written by Dr. Rothbard, and first published on Apr 18, 2012.
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