What type of autoimmunity is Sjogren syndrome?

Immunology Immunopathology
1

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.

2

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.