Autoimmune Concepts Flashcards
What is autoimmunity and how does it come about
What triggers it
2 types of tissue attacked by the disease
- it is a condition when the immune system responds against self antigens due to loss of tolerance ( immune system unable to differentiate between self and non-self antigens )
- by the environment In genetically susceptible people
- specific organ or large number of tissue. ( systematic ) due to specific antigen being attacked
How is autoimmunity avoided by the body
-elimination of auto reactive lymphocytes during development ( negative selection )
What is an autoimmune disease and the 2 causes
-a disease that occur when the immune system attacks self antigens
1 humoral ( by auto antibodies ) 2 cellular ( auto reactive T cells )
Types of systems attacked by autoimmune diseases
1 specific
2 numerous organs ( systematic )
Function of MHC antigens
Describe MHC molecules
- recognition of self from non-self by immune system
- are a product of cluster of genes in human genome known as major histo compatibility complex of chromosome 6p21
How do B and T cells bind to epitopes
- T lymphocytes cell receptors need epitome bound to MHC to recognize
- B cell receptors bind directly to epitomes
Describe MHC 1 molecules and the genes used to make them
- made by all nucleated cells
- has deep groove to bind to endogenous epitopes ( those made in cell )
-HLA ( A B C )
Describe the MHC 2 molecules and the genes used to make them
- Made only by antigen presenting cells ( APC ) , macrophages, dendritic cells and B lymphocytes
- deep groove to bind to exogenous epitopes
-HLA ( DR DQ DP )
Describe the 2 causes of autoimmunity
1 Changes in self antigen - are altered either by ( infection , medication or radiation ) and no longer recognized as self. Binding of self and non self. Overproduction of self.
2 changes in immune system - mutations to normal antibodies causes pathogenicity. Problems in lymphocyte development
-genetics causing central tolerance problem
Mechanisms by which tolerance breaks down
- failure to deal with auto reactive lymphocytes ( gene mutations )
- abnormal presentation of self antigens ( self and non bind )
- epitope spreading ( once autoimmunity starts it spreads to other epitopes
Are T lymphocytes made to tolerate cells with self MHC 1 and self peptide
What do they attack instead
What causes alternated complexes
-yes
/non self antigens
-transformation, genetic disorders, infection
Why is a transplant rejected and mitigation
/if it has non matching MHC it is seen as non self and acted upon vigorously by immune system
- matching donors
- immunosuppressive medication
When will system fight cancer
What would the immune system fight cancer
- when functioning normal and not suppressed
- when cancerous cells are diff enough from normal tissue
- when cancerous tumor is large enough
- cause transformation from normal to cancerous involves metabolic, biochemical and genetic changes and immune may see it as non self and attack
2 other causes of autoimmunity
1 molecular mimicry ie cross reaction
2 epitope spreading. Ie once specific autoimmunity activated may spread to other self epitopes
2 types of autoimmunity Examples of autoimmunity for Thyroid Brain Stomach Adrenal Pancreas
1 organ specific 2 non organ specific ( systematic ) - hashimoto’s thyroditis - multiple sclerosis - pericinous anemia - addinsons disease - diabetes mellitus
