Hypersensitivity and Autoimmune Disease Flashcards
What is autoimmune disease?
A failure or breakdown of immune system that maintains tolerance to self tissues
What is the loss of tolerance to self tissues due to?
abnormal selection or lack of control of self-reactive lymphocytes (B and T-cells)
What may damage in different autoimmune diseases may result from?
Different effector mechanisms
What are two risk factor of developing autoimmune disease?
Environment and genetics
What is usually used to cure autoimmune diseases?
Blanket immunosuppression.
What is blanket immunosuppression?
Suppressing the immune system in order to supress the symptoms of the autoimmune disease.
What is a side effect of blanket immunosupression?
Infection
What is the tactic to tackle autoimmune diseases?
Come up with more targeted selective approach’s meaning target the aberrant immune activation while leaving the rest of the immune system intact
Name the disadvantages of autoimmune disease.
yh ik that sounds weird haha, disease doesn’t have any advantages rlly but shhh get on w it
Typically chronic long-term disorders [low mortality but high morbidity]
Treatments limited to dealing with the symptoms rather than curing the disease
Treatments e.g., steroids carry their own risks
Patients require intense, careful management and treatment costs run into billions worldwide
What do we not know aboout autoimmune diseases?
How it is caused
How to treat it
What is the actual damage from autoimmune diseases caused by?
Hypersensitivity responses.
There are four types of Hypersensitivity responses, what are they?
Type 1, 2 ,3 ,4
Which types of Hypersensitivity responses are antibody mediated?
Types 1,2,3
Which types of Hypersensitivity responses are T cell mediated?
Type 4
Describe the sequence of events in immediate hypersensitivity reactions for Type 1.
Immediate hypersensitivity diseases are initiated by the introduction of an allergen, which stimulates TH2 reactions and IgE production. IgE sensitizes mast cells by binding to FcdeltaRI, and subsequent exposure to the allergen activates the mast cells to secrete the mediators that are responsible for the pathologic reactions of immediate hypersensitivity.
Desribe Type 1.
- Relies on presence of antibody IgE
2.Produces allergy
Describe type 2 and 3.
- Reliant on antibody IgG
- Type 2 can cause Rheumatic fever
- Type 3 can cause Rheumatoid arthritis
Out of type 2 and 3, which response is predictable and which is more spontaneous?
Type 2- predictable
Type 3- spontaneous
Describe mast cell actiavtion.
- Antigen binding to IgE cross-links FcΕRI molecules on mast cells, which induces the release of mediators that cause the hypersensitivity reaction
- Other stimuli, including the complement fragment C5a, can also activate mast cells
Define atopy
Predisposition to allergy
Type 2 is about specificity. What does this mean?
It is targeting a specific antigen.
Give an example of type 2/3 hypersensitivity.
Antibodies may bind specifically to tissue antigens and the recruited leukocytes cause tissue injury
Where may complexes of antibodies and antigens be formed?
What do these complexes induce?
Formed in circulation and deposited in blood.
Can induce vascular inflammation, and subsequent ischemic damage to the tissues. Can also lead to depletion of the cells and functional abnormalities.
What is the difference between type 2 and type 3?
Type 2 and type 3 hypersensitivity both result from the same class of antibody, called IgG. The difference between them lies in the form of antigens that generate a response.
What is type 4?
Occur in response to contact with certain allergens resulting in contact dermatitis
Name the two ways type 4 can be mediated.
Cytokine mediated inflammation
T-cell mediated cytotoxicity
Name some T-cell mediated immunologic diseases.
Type 1 diabetes
Multiple sclerosis
Rheumatoid artheritis
If you have the allele DR4, what does this mean?
You are four times more likely to develop rheumatoid artheritis.
Compare genetic factors and environmental factors relating to developing an autoimmune disease.
Genetic background of an individual may pre-dispose them to an autoimmune disease
->Complex, multi-factorial, but can be other independent factors not related to genetic background.
Environmental factors- most likely is prior infection.
->Other factors may include drugs, trauma, food
What is molecular mimicry?
The immune system makes a response against the pathogen but that response is then cross reactive with a self tissue and then causes autoimmune damage.
Define immunological tolerance.
State of unresponsiveness to specific antigen, either self or foreign antigens.
->as a state of indifference or non-reactivity towards a substance that would normally be expected to excite an immunological response
What does immunological tolerance prevent??
Adaptive responses that are damaging (immune pathology) like BSR responses, particularly B cells and T cells
How can immunological tolerance be expolited?
Microbes and tumours.
->tumours create an environment that the T cells do not function as well in so tumour may escape from the immune system.
For each T cell, how many specificities is there?
> 1011 specificities
Where do T cells develop?
Thymus, just above the heart
Name the two categories of autoimmune disease.
Systemic or organ specific
Describe the process of systemic autoimmune disease.
Autoimmune process is diffuse is spread throughout the body
Affects more than one organ - not necessarily the same ones in different individuals
Describe the process of organ specific autoimmune disease.
Autoimmune process directed against one organ
For example, Type 1 Diabetes - pancreas
Name some symptoms of Systemic lupus erythematosus
Butterfly rash on face, fever, mouth ulcers, arthritis, painful joints.
Is Systemic lupus erythematosus systemic or organ specific?
Systemic
Name some symtoms of type 1 diabetes.
Thirst, extreme urine output.
->renal failure, heart disease, blindness
Why do individuals w type 1 diabetes pee a lot?
lol for my own interest
Drink a lot to try and balance sugar in the body
when im typing this it seems like common sense lollll
What is loss of tolerance due to?
Due to abnormal selection or lack of control of self-reactive lymphocytes (B and T-cells)
