Autoimmune disease Flashcards
Describe the double-edged sword concept around immunity
Immune system must be able to fight infection and tolerate self
Prevent autoimmunity without being immune deficient
What is autoimmunity?
Occurs when an immune response is mounted against a self antigen
Caused by loss of tolerance
TRUE or FALSE
All autoimmune conditions lead to disease
FALSE
Some have subclinical presentations
Which categories can autoimmune diseases be split into?
Organ specific - it is clear the specific organ which is targeted
Systemic - affects multiple parts of the body
Examples of organ-specific autoimmune diseases
Type I diabetes
Goodpasture’s
Multiple sclerosis
Grave’s diseases
Hashimotos thyroiditis
Examples of systemic autoimmune diseases
Rheumatoid arthritis
Scleroderma
Systemic lupus erythematosus
Why do mechanisms of peripheral tolerance exist?
Because central tolerance occurring in the thymus is incomplete
Where does peripheral tolerance take place?
Lymph nodes
Spleen
Secondary immune organs
What is a key component of peripheral tolerance?
T regulatory cells
Studies proving the importance of T regulatory cells in peripheral tolerance
Studies on Treg deficient mice showed they have dysregulated immune responses
They develop lymphadenopathy and splenomegaly
Due to lack of cell control
Marker for T regulatory cells
Foxp3
What is IPEX?
Immune dysregulation polyendocrinopathy enteropathy X-linked syndrome
It is an aggressive autoimmune disorder leading to early death
What is the cause of IPEX?
Mutations in the Foxp3 gene
When is the onset of IPEX?
Within first months of life
Presentation of IPEX
> 80% IPEX patients have type I diabetes, IBD and allergy
Pathophysiology of IPEX
Individuals make T cells but are not able to make Treg cells
What causes autoimmunity?
Mixture of many factors including genes, environment and failed immune regulation
What gene plays the largest contribution to the genetic susceptibility of autoimmunity?
HLA genes
Proof that more that genetics is involved in the development of autoimmune disease
Individuals with the same mutation to the MHC have different phenotypes
Some develop autoimmunity, some do not
Low concordance rates between twins
MHC allele linked to increased risk of ankylosing spondylitis
HLA-27
MHC allele linked to increased risk of rheumatoid arthritis
HLA-DRB1
MHC allele linked to increased risk of type I diabetes
HLA-DRB1