Type II and III Hypersensitivity Flashcards
What is Type II Hypersensitivity?
When abnormal antibodies are directed against a target organ.
Name six examples of Type II Hypersensitivity.
- Autoimmune hemolytic anemia
- Autoimmune thrombocytopenia
- Goodpasture’s
- Hyperacute graft rejection
- Myasthenia Gravis
- Grave’s Disease
What is going on with Myasthenia Gravis?
Abs against Ach receptors on muscle leads to degradation of the receptors and impaired muscle function.
What is going on with Grave’s disease?
Abs against TSH receptors in the thymus causes constant stimulation of the receptors and overproduction of thyroid hormones.
What is Type III Hypersensitivity?
When antibody-antigen complexes get trapped in small vessels of the body, bind complement, and cause vessel wall damage.
Specifically how are blood vessels damaged during a Type III hypersensitivity reaction?
Complement proteins C3a and C5a recruit neutrophils (polymorphonuclear leukocytes) to the area, which are not able to eat the complex, so they just end up dying and releasing their lysosomal enzymes at the site –> vasculitis.
If you find that a patient with impaired kidney function (high albumin in urine) also has low serum complement protein levels, what is the likely diagnosis?
Type III hypersensitivity reaction - comsumes complement proteins.
What is ANA? What does a positive test for high ANA indicate?
Anti-nuclear antibodies are high in patients with systemic lupus erythematosus (SLE).
What is post-streptococcal glomerulonephritis?
Circulating anti-streptococcal antibodies combine with strep Ags and the complexes get trapped in the glomeruli.
What causes serum sickness?
Type III hypersensitivity due to treatment with serum fron another animal (anti-venom).
What types of hypersensitivity reactions can drugs like penicillin cause?
Any!
What is an Arthus reaction (localized immune complex disease)?
It is a localized Type III reaction that occurs when an individual already has antibodies to an antigen. Example is when someone gets a tetanus booster and their arm is sore.
What is Farmer’s lung and what causes it?
It is a combined Type III and IV reaction in the lung caused by actinomycete organisms in moldy hay and bird poo.
Which antibody isotype is most often involved in Type III hypersensitivity?
IgG
