cytotoxic Reaction

Question 1

type 2 hypersensitivity

Answer 1

-abnormal antibody directed against a target organ causes destruction of the cell targer via complement mediated lysis or by ADCC (NK recognizes cell by Ab)

Question 2

examples of type 2 hypersensitivity

Answer 2

• autoimmune hemolytic anemia
• autoimmune thrombocytopenia
• goodpastures syndrome (IgG for the basement mem of the glomerulus and the alveoli)
• hyperacutes graft rejection
• anti-receptor antibody diseases (myasthenia gravis and graves disease)

Question 3

myasthenia gravis

Answer 3

• abnormal antibodies to the acetylcholine receptors
• binding of the antibody causes internalization of the Ach receptos and degradation
• when patient sleeps, they get resynthesizaed so in the morning they feel fine but by noon they are weak

Question 4

graves disease

Answer 4

• due to stimulatory autoantibodies
• antibody binding TSH receptor causing the thyroid to make thyroid hormone
• causes goiter and fat deposition behind the eye because it binds fibroblast TSH receptors

Question 5

type 3 hypersensitivity immune complexes

Answer 5

• Ag-Ab complexes are trapped in the small vessels of the body
• binding of complement triggers an inflammatory response which damages blood vessels
• vasculitis
• C3a and C5a are chemotactic for neutrophils
• neutrophils degranulate in vessel wall releasing lysosomal enzymes which damage cell wall
• complement levels may fall as this process consumes its proteins

Question 6

systemic lupus erythematosus

Answer 6

this is a systemic immune complex

• antigen is DNa and other nuclear components
• Ab is anti-DNA and other anti-nuclear Ab’s
• complexes are trapped in the small vessells of the skin kidney and joints

Question 7

-post streptococcal glomerulonephritis

Answer 7

• circulating anti streptococcal antibodies combines with streptococcal antigen
• complexes get trapped in the glomeruli
• systemic immune complex disease

Question 8

serum sickness

Answer 8

• patients treated with serum from an animal such as a horse will make anti-horse antibodies
• systemic immune complex disease

Question 9

drug reactions

Answer 9

• could be from penicillin
• systemic immune complex disease
• these drugs can also be reponsible for type 1,2,3, and 4 hypersensitivity reactions

Question 10

localized immune complex disease

Answer 10

• appears when antigen is introduced into an individual who already has antibodies
• immune complexes at the site attract neutrophils and produce inflammation
• this can be from tetanus toxin given to a person who already has tetanus antibodies
• hypersensitivity pneumonits such as farmers lung or bird fanciers disease

Question 11

farmers lung

Answer 11

• actinomycete organisms are present in mouldy hay
• repeated inhalation of these organisms stimulates systemic Igg antibody production
• further inhalation produces immune complexes in the lung and an Arthus reaction (localized)
• later there is infiltration by T cells with cytokine production andd further inflammation
• therefore this is a mixture of a type 3 and type 4 reaction