Type II Hypersensitivity Flashcards
How is Graves Disease classified as a (type II hypersensitivity) antibody-mediated disease?
Abs form against and bind to the TSH receptor. This interaction stimulates the TSH receptor resulting in hyperthyroidism.
What is the immune mechanism in type II hypersensitivity?
Foreign antigen on cell surface induces Ab formation. Ab binds to antigens of cells, fixes complement and induces lysis/phagocytosis. Ab can also bind to Fc receptors on NK cells to induce antibody-dependent cell-mediated cytotoxicity.
How is myasthenia gravis classified as a (type II hypersensitivity) antibody-mediated disease?
Abs form against and bind to the acetylcholine receptors on muscle inhibiting ACh binding with its receptors resulting in muscle weakness, paralysis.
What are other clinical examples of (type II hypersensitivity) antibody-mediated disease?
Autoimmune hemolytic anemia, autoimmune thrombocytopenic purpura, Goodpasture’s syndrome, pemphigus vulgaris, pernicious anemia, rheumatic fever, transfusion reactions, erythroblastosis fetalis, drug-induced rxns, hyperacute graft rejection
What are diagnostic tests for type II hypersensitivity?
1) Check complement levels. Levels will be low
2) Check for presence of immune complexes via tissue biopsy and immunofluorescence
How can you prevent type II hypersensitivity rxn?
1) Blood cross-matching
2) Rhogam injections for Rh- mothers
3) supportive plasmapheresis or dialysis
4) immune suppressants - corticosteroids
Why does the body have ADCC?
To kill cells expressing viral or tumor antigens
What is the mechanism in transfusion rxns causing type II hypersensitivity?
Pre-formed natural anti-ABO Abs, anti-Rh Abs and other anti-RBC Abs mount immune response against antigens and Rh proteins on RBCs.
What is the mechanism in erythroblastosis fetalis?
Rh incompatibility of present fetus induces anti-Rh Abs in mother-IgG that cross the placenta and attack red cells of subsequent children
What is the mechanism of autoimmune hemolytic anemia?
Autoimmune response against RBCs generally after an infection.
What is the mechanism of Goodpasture’s syndrome?
Abs bind to type IV collagen in basement membrane in the pulmonary alveoli and glomerulus resulting in pulmonary hemorrhage and glomerulonephritis.
What is the mechanism in hyperacute graft rejection?
Preformed Abs against transplantation antigens (e.g. HLA) cause immediate, severe, non-reversible damage to graft
