Autoimmunity Flashcards
Define Autoimmune Disease
Tissue damage or disturbed physiological function due to an autoimmune response
Autoimmune diseases result from the body’s immune system attacking its own tissues.
What is autoimmunity?
Immune response against a self-antigen or antigens
Not all autoimmunity leads to tissue damage.
Contrast organ-specific and non-organ specific autoimmune disease.
- Organ specific: Affect single organs
- Non-organ specific: Affects multiple organs
Organ-specific diseases target specific organs, while non-organ-specific diseases have a broader impact on the body.
What is the role of HLA molecules in autoimmune disease?
They are strongly associated with the breakdown of immunological tolerance, affecting self vs. non-self recognition
HLA (Human Leukocyte Antigen) molecules play a crucial role in the immune response.
What is the epidemiology of autoimmune diseases?
- 3-5% of the population
- Peak onset: 15-65 years
- More common in women
Exceptions include Type 1 Diabetes mellitus and ankylosing spondylitis.
What are the mechanisms by which immunological tolerance arises?
- Central tolerance
- Peripheral tolerance
Tolerance is essential to prevent autoimmunity by eliminating or downregulating self-reactive T and B cells.
Define central tolerance.
Occurs during lymphocyte development; self-reactive T and B cells are eliminated before becoming immunocompetent
Most active during fetal life but continues throughout life.
What is peripheral tolerance?
Mechanisms that control autoreactive cells that evade deletion and reach peripheral tissues
Peripheral tolerance is necessary as not all self-antigens are presented during central tolerance.
What factors contribute to the aetiology of autoimmune disease?
- Genetic factors
- Environmental factors
- Hormonal influences
- Infections
Autoimmune diseases often arise from a complex interplay of these factors.
What is the significance of somatic hypermutation in B cells?
It poses a theoretical risk of making B cells reactive against self-cells
This process is crucial in the generation of high-affinity antibodies but can also lead to autoimmunity.
True or False: Every individual harbors autoreactive cells.
True
Autoreactive cells are a normal part of the immune repertoire but are usually kept in check by tolerance mechanisms.
Fill in the blank: The immune system’s failure to maintain tolerance leads to _______.
[autoimmunity]
Breakdown of tolerance results in immune reactions against self-antigens.
What is molecular mimicry?
A mechanism where microbial peptides resemble self-peptides, potentially triggering an autoimmune response
This can lead to the immune system mistakenly attacking the body’s own tissues.
What are the primary mechanisms of tissue damage in autoimmune diseases?
- Antibody-mediated mechanisms
- Cell-mediated mechanisms
Both pathways contribute to the pathology observed in various autoimmune diseases.
What are common treatments for autoimmune diseases?
- Replacement therapy (e.g., Insulin for T1DM)
- Immunosuppressive medications
There are currently no cures for autoimmune diseases, only treatments to manage symptoms.
What is the role of regulatory T cells (Tregs) in peripheral tolerance?
Active suppression of self-reactive T cells through cytokine secretion and cell contact-dependent mechanisms
Tregs are essential for maintaining immune tolerance and preventing autoimmunity.
What is Graves’ disease?
An autoimmune disorder that affects the thyroid gland, causing hyperthyroidism
Graves’ disease is characterized by the overproduction of thyroid hormones.
What is myasthenia gravis?
An autoimmune neuromuscular disease leading to varying degrees of skeletal muscle weakness
It is caused by an autoimmune attack on acetylcholine receptors.
What are haemolytic anaemias?
A group of disorders characterized by the premature destruction of red blood cells
This can lead to anemia due to a reduced number of circulating red blood cells.
What is pemphigus?
An autoimmune blistering disorder of the skin and mucous membranes
It results from the loss of adhesion between skin cells.
What is the primary goal when treating autoimmune diseases?
Controlling the immune response
Treatments can vary widely depending on the specific autoimmune disease.
What is a key characteristic of treatments for autoimmune diseases?
No cures, only treatments
Some treatments may work across several diseases but can exacerbate others.
What is insulin replacement used for?
Type 1 Diabetes Mellitus (T1DM)
T1DM is an autoimmune condition where the pancreas produces little or no insulin.
What is levothyroxine replacement used for?
Hashimoto’s thyroiditis
Hashimoto’s thyroiditis is an autoimmune condition that leads to hypothyroidism.
Which of the following is a non-organ-specific (systemic) autoimmune disease?
Systemic Lupus Erythematosus (SLE)
Other examples include Myasthenia Gravis and Pernicious anaemia.
What does a high concordance rate for monozygotic vs dizygotic twins in type 1 diabetes indicate?
A strong genetic element
This suggests that genetics plays a significant role in the development of type 1 diabetes.
What is HLA-B27 a risk factor for?
Ankylosing spondylitis
HLA-B27 is also associated with other autoimmune conditions, including rheumatoid arthritis.
