abnormal immune response Flashcards
3 major types of abnormal immune responses?
- immunodeficiency
- hypersensitivity
- autoimmunity
what is immunodeficiency?
-partial or complete loss of immune response
what are the 2 categories of immune response?
- antibody mediated (b cells)
- t cell response
immunodeficiency- which kind of response of the immune system is deficient?
either or! it could be one or the other or both
what is the primary immunodeficiency?
genetic or congenital
-immune system fails to develop (example the thymus)
what is secondary immunodeficiency?
acquired (post-natal)
- example: infection (AIDS, HIV destroy T helper cells)
- cancer treatment, some drugs
whats a primary disease?
stand alone disease, developed on its own
what is a secondary disease?
- pneumonia developing because of the flu, not a stand alone disease
- develops because of another diseas
what are the types of immunodeficiency (5)?
- B cell disorders–> impaired antibody production- either primary or secondary
- T cell disorder–> T cell function impaired
- T and B disorders–> nearly no immune response
- complement disorders (integral part of IR!)
- disorders of phagocytosis
treatment for immunodeficiency? (2)
- replacement therapy- giving the body antibodies (gamma globulins), supplementing the immune response
- marrow transplant?? if it is genetic or congenital
- very complex, usually last resort
what is hypersensitivity?
exaggerated/inappropriate immune response.. never better, always a problem
4 types of hypersensitivity? (4)
Type 1- Allergy or IgE mediated H
Type 2- cytotoxic or tissue specific H
Type 3- Immune complex H
Type 4- T cell mediated or delayed H
acronym for hypersensitivity types
ACID
difference between the first 3 types of hypersensitivity and type 4
first three types are driven by antibodies
-type 4 is mediated by the T cells
What is shock?
acute hypo-perfusion due to CV failure—> hypoxia, systemic
types of shock? (4)
cardiogenic
hypovolemic
obstructive
distributive
what is anaphylactic shock? what does it follow?
follows severe allergic reaction (type 1 H)
-will cause death unless reversed
process of anaphylactic shock?
1. allergen--> mediator released--> increased systemic vasodilation--> increased capillary permeability--> circulatory failure---> edema
what is septic shock?
similar to anaphylactic but follows severe infection
- also vasodilatory, multi organ failure
- extension of type 1 hypersensitivity
what is Type 1 hypersensitivity? (onset, why does it occur)
- common form
- mediated via IgE antibody, due to allergens
- acute onset, occurs within minutes
what happens the first time a person makes contact with an allergen?
Th2 cytokines produced (mediated b Il-4)--> B cell stimulation--> plasma cell formation ---> leads to production of antibodies ---> igE binds to the mast cell
what happens after re-exposure to an allergen?
allergen binds to IgE on mast cell—>
inflammation mediator release–>
inflammation (prostaglandin and histamine released at site of exposure)
—> at site, erythema, pruritus, swelling
what is type 2 hypersensitivity?
- mediated via IgG or IgM
- antigens are developed during development that are self, and non-self
- endo and exogenous antigens are mistargeted by antibodies
antigens- endogenous vs exogenous
endogenous are your antigens
exogenous are human antigens but they are from someone else so your body reacts to it
what is type 3 hypersensitivity?
The immune complex formed from antigen and antibody is not removed/degraded, so it deposits in the tissues
where does the IC deposit in type 3 usually?
on the surface of endothelium–> abnormal, form of injury
what happens when the IC deposits in tissues (type 3)?
- defense cells come and attempt to remove it, triggers inflammation and damages vessels
- complement is activated
why are the ICs not degraded in type 3?
one of 2 reasons usually
- some of the ICs are too tiny to be recognized by enzymes that break down ICs
- the immune complexes are refractory to breakdown (resistant)
what are 2 examples of type 3 hypersensitivity?
- glomerulonphritis
- rheumatoid arthritis
what is different about type 4 hypersensitivity?
T cell mediated! no antibodies involved
what happens in Type 4?
macrophage presents bacterial cell (antigen)—> T cell is synthesized–> cytotoxic T cell
BUT… now the T cell destroys the macrophage too causing inflammation and tissue damage
2 responses of type 4?
- direct response (very quick)
- delayed (occurs later because T cells produce mediators but this can take up to 72 hours, and it requires these mediators like lymphokines
what is an example of type 4?
tuberculin skin test
what is autoimmunity?
chronic problem, immune system is targeting cells within our body, the entire immune system!
when self tolerance of antigens is lost, what will happen?
immune system will recognize “self” antigens as “foreign”
so, T cells and antibodies target self antigens
-causes inflammation, tissue damage, necrosis
what can self-tolerance be lost by? (3)
- molecular mimicry
- epitope on a bacteria similar to the epitope on our self antigens confuses the immune system—> thus antigen is mis-identified - abnormal T cell function
- example loss of suppression - exposure of sequestered antigens in disease
- immune system disregard or does not process the antigens that are internalized
