Hypersensitivty- type II, III, IV Flashcards
What does the term hypersensitivity mean?
The antigen specific immune response that are either inappropriate or excessive and result in harm to host
How can you trick the immune system?
Believe that have the disease so causes an immune response
- vaccination
What are exogenous substances?
Non infectious substances (allergy)
Infectious microbes
Drugs e.g. Penicillin
What are intrinsic antigens?
Infectious microbes (mimicry- autoimmune- has parts that are like hosts microbes) Self antigens
What is type I or immediate
Allergy
Environments non infectious antigen
IGE
What is type II hypersensitivity?
AntiBody mediated
IGM
What is type III hypersensitivity?
Immune Complexes mediated
IGG
What is type IV hypersensitivity?
Cell mediated- Delayed
Environmental infectious agents and self antigens
What mechanisms cause hypersensitivity?
The immune repossess that are employed to fight host infection
However too much- overreaction
What is the difference between type II and III?
Type III is against soluble
Membrane bound type II
What is sensization phase?
First encounter with the antigen
Activation of APC and memory effector cells
If an individual has been previously exposed to an antigen what are they said to be?
Sensitised
What is the effector phase?
Pathological reaction upon re exposure to the same antigen and activation of the memory cells of the adaptive Immunity
When does type II hypersensitivity develop?
5-12 hours after exposure
What kind of antibodies does hypersensitivity type II involve?
IGM or IGG
What does hypersensitivity type II target?
Cell bound antigens
E.g. Blood group antigens, Rhesus D antigen,self antigens
What does type II hypersensitivity cause?
Tissue or cell damage
Change in cell function
How can type II sensitive cause cell damage?
by antigen dependant cells when in natural killer cells bind to antibody through FRC receptor and release toxic radicals through to the cell itself
Self antigen- usually present in red blood cells, activate complement and destroyed, also happens in platelets
What can complement act on?
Many cells in innate immunity, adaptive immunity and disposal system
What is an example of a disease caused by type II hypersensitivity? IGM
Haemolytic transfusion reaction
What is haemolytic transfusion reaction?
Life threatening condition
Shock
Kidney failure
Circulatory collapse and death
What is the Immune mechanism of haemolytic transfusion reaction?
Incompatible in the ABO of rhesus D antigens
Donor red blood cells destroyed by recipients Immune system
Red blood cell lysis induced by type II hypersensitivity by the naturally occurring antibodies
What is an example of type II sensitivity? IGG
Rhesus posture father and Rhesus negative mother
In response the mother will produce anti Rhesus antibodies
If pregnant again her antibodies will cross the placenta and damage fatal red blood cells
Causes haemolytic disease of the newborn- anaemic
What is treatment for problems with Rhesus positive father and negative mother?
Give Rhesus d immune globulin human
Prevents mother getting sensitised
What is Graves’ disease?
Increased thyroid activity
Antigen is TSH receptor
What is myasthenia gravis?
Impaired neuromuscular signalling
Antigen=acetylcholine receptor
What are the therapeutic approaches for type II hypersensitivity tissue cell damage?
Immune suppression
Plasmapheresis
Splenectomy
Intravenous immunoglobulin
What are the therapeutic approaches for type II hypersensitivity physiological damage?
Correct metabolism
Replacement therapy
What is plasmapheresis therapy?
Plasma is filtered and discarded and serum is given
Short term relief and allows healing of damaged tissue
When is plasmapheresis therapy used?
Myasthenia gravis
Goodpastures syndrome
Graves’ disease
When does type III hypersensitivity develop?
Within 3-8 hours
What does type III hypersensitivity target?
Soluble antigens e.g. Foreign infection or endogenous (self antigens)
What does type iii hypersensitivity cause?
Tissue damage
What are the key factors affecting IC pathogenesis ?
Complex size
Host response- low affinity antibody or complement deficiency
Local tissue factors
What is type iii hypersensitivity efffect?
Multiststem disease
What are the two main diseases that type III hypersensitivity cause?
Rheumatoid arthritis
Glomerulonephritis
What are the features of rheumatoid arthritis?
Rheumatoid factor antigen IGG
Episodes of inflammtion and remission
What is glomerulonephritis?
Infectious
Bacterial endocarditis
Hepatitis b infection
What is systemic lupus erthematosus?
Every patient unique
Do-DNA antigen
Mainly women
Repeated miscarriage
What are the features of type IV hypersensitivity?
Develops within 24-72 hours
Involves lymphocytes and macrophages
What are the subtypes of type IV hypersensitivity?
contact hypersensitivity- eczematous rash
Tuberculin hypersensitivity- induration and swelling
Granulomatous- tissue damage, granuloma- walls off infected cells
What diseases are caused by type IV hypersensitivity exogenously?
Granulomatous hypersensitivity- tuberculosis, leprosy, schistosomiasis, sarcoidosis
Contact hyoersensitiy- nickel, poison ivy, organic chemicals
If someone has beeen infected with tuberculosis how would you find out if they are sensitised?
Antigen injected and processed by antigen presenting cells
T cells recognise antigen and release cytokines which react on endothelium
Pathogocytes and plasma to site and causes visible lesion
What diseases are caused by type IV hypersensitivity endogenously?
Autoimmune disease e.g. Pancreatic islet cells- insulin dependant diabetes mellitus
Thyroid gland- Hashimoto’s thyroiditis (cd8+ T cells and antibodies)
IGG- rheumatoid arthritis
What are the therapies for type iii and IV hypersensitivity?
Anti inflammatory drugs e.g. Non steroid, corticosteroids, second drugs of steroid sparing agents
Monoclonal antibodies
B cells and T cells
Will have more as time goes on
