Category:Autoimmune Diseases

Antibody Mediated Autoimmune Diseases

Cell mediated autoimmune diseases

Rheumatoid Arthritis-Brian Catchpole RVC 2008

Diabetes Mellitus-Brian Catchpole RVC 2008

1. Rheumatoid arthritis

Pathogenesis:

• Type IV hypersensitivity: CD4 Th-1 cell mediated.
• Macrophages phagocytose self antigens and can present peptides on their MHC Class II molecules. The autoreactive TH-1 cells release IFN-gamma which activates macrophages to release prostaglandins, MMP enzymes and TNF-alpha (pro-inflammatory mediator), see diagram. These cytokines cause inflammation and tissue destruction.

2. Diabetes Mellitus type I

Pathogenesis:

• Type IV hypersensitivity
• The CTLs think that all the beta cells in the pancreas are infected by a virus, as it wrongly detects a self antigen presented by the MHC class I on the surface of the cell as foreign.
• Autoreactive CD8+ CTLs are inadvertently activated, destroying the beta cells, thus preventing the secretion of insulin and causing diabetes type 1 (see diagram).

3. Hypothyroidism (lymphocytic throiditis)

Pathogenesis: Type IV hypersensitivity

• T cell mediated

4. Hypoadrenocorticism (Addisons disease)

Pathogenesis: Type IV hypersensitivity