What type of autoimmunity is Sjogren syndrome?

Greetings everyone.

Is anyone aware what type of hypersensitivity is Sjogren or Hashimoto?

Since lymphocyte infiltration is a prerequisite (even without and before circulating Igs) I conjecture they are a type IV case. However, I have found all kind of references (type III, II and IV) - perhaps an issue of older literature

Thanks in advance.

Hi Sachin Sharma

You are right about the existing confusion. however the literature now has more evidence towards Type IV. this can be explained by the mechanism of Hashimoto where

  • Chronic inflammation caused by autoreactive T cells (CD4+ and CD8+ T cells) that infiltrate the thyroid gland and cause thyrocyte destruction.
  • Additionally, autoantibodies (anti-thyroglobulin and anti-thyroid peroxidase) are present, which may contribute to Type II hypersensitivity mechanisms through complement activation and antibody-dependent cell-mediated cytotoxicity (ADCC).
  • However, the primary mechanism is still T-cell-mediated cytotoxicity (Type IV).
  • Why Confusion Exists:
  • The detection of circulating autoantibodies led earlier literature to classify it as Type II hypersensitivity.
  • The consensus now is that Type IV is predominant, with a minor Type II component.