In some people with autoimmune disease, patterns showing a dominance to either the Th1 or Th2 pathway have been shown. Although there are exceptions, the following table shows the conditions that are most commonly associated with a Th1 or Th2 dominant state:
TH1 dominant conditions:
Type I diabetes
Chronic viral infections
TH2 dominant conditions:
Inflammatory Bowel Disease
Multiple chemical sensitivity
When the Th1 cells of the immune system are overactive, they can suppress the activity of Th2 and vice versa. This can be problematic because these two components of the immune system function in a delicately balanced relationship. In the case of autoimmune disease, imbalance can further the attack on healthy tissue, thereby worsening symptoms.
Although research can lump those with certain conditions under the Th1/2 categories, in reality they can be all over the map. For instance, although most Hashimoto’s patients present a Th1 dominance, some can be Th2. It is also possible to have both Th1 and Th2 simultaneously overactive or under-active. Pregnancy can shift the immune system temporarily to Th2, which is why a lot of women find out they have Hashimoto’s after they give birth and their immune system returns to Th1 dominance.