Diseases of Immunity Flashcards
What is central tolerance and where does it occur?
it is learned tolerance prior to release from generative organs; occurs in the thymus and in the bone marrow
What happens if B cells recognize and react to their own self antigens?
they have the opportunity for receptor editing or they undergo apoptosis
What are the mechanisms of peripheral tolerance?
T regulatory suppression and anergy
How does anergy occur?
T lymphocytes have inhibitory receptors; our self cells express ligands and if the T cells bind to these ligands on the self cell they undergo anergy
what are the inhibitory receptors that are found on T lymphocytes that are important in the process of anergy?
CTLA and PD-1
what do our self cells express that can bind to the T lymphocytes and induce anergy?
CD 80/86 or PDL1
What are three different mechanisms for autoimmune diseases?
susceptibility genes, molecular mimicry, and epitope spreading
what autoimmune diseases occur via the mechanism of susceptibility genes?
ankylosing spondylitis, rheumatoid arthritis, and Crohn’s disease
what autoimmune diseases occur via the mechanism of molecular mimicry?
rheumatic heart disease
what autoimmune diseases occur via the mechanism of epitope spreading?
oral lichen planus
What is the susceptible gene that is associated with ankylosing spondylitis?
B27
what is ankylosing spondylitis/ how does it present?
it is a hereditary inflammatory condition of the joints; young patients present with severe neck and back pain; bamboo spine
What is the susceptible gene associated with rheumatoid arthritis?
PTPN22 (protein tyrosine phosphatase)
what does the polymorphism of the PTPN22 gene lead to?
there is not adequate elimination of the self reactive clones, so you don’t suppress your T cell response; leads to increased inflammation; they have a direct influence on reducing B-cell and T-cell tolerance
What is the susceptible gene associated with Crohn’s disease?
NOD-2 gene
what happens in cases of polymorphisms of the NOD-2 gene?
paneth cells in the intestinal epithelium are ineffective at killing microbes; so there is a significant overgrowth of bacteria and an accompanying inflammatory response
what is molecular mimicry?
when there is antigenic similarity between true pathogens and native tissues leading to autoimmunity
What is the mechanism of rheumatic heart disease?
molecular mimicry
What occurs during epitope spreading?
some of our antigens are hiding intracellularly or they are just anatomically hidden; this means that if something happens to breakdown the intact structures or cells, we can spill out antigens that our immune system has never seen before
during oral lichen planus, what happens during the initial T response?
leads to keratotic lesions in the oral and conjunctival mucosa, which leads to basement membrane disruption exposing antigenic proteins (lichen planus)
what is the secondary disease that follows Lichen Planus?
Pemphigoid (a secondary B cell response)
If you suspect an autoimmune disease might be occurring in your patient, what would be one of the first test you order?
ANA (anti-nuclear antibody) test
if a patient tests positive for ANA, what test would you look for to be positive if they had lupus?
anti DS DNA or anti smith
if a patient tests positive for ANA, what test would you look for to be positive if they had Sjogren syndrome?
Anti Ro/ SS-A or Anti La/ SS-B