Which mechanism is involved in type II hypersensitivity reaction?
Type II hypersensitivity reactions are mediated by antibodies directed against antigens on the surface of tissue or cells so that the tissue or cell is destroyed or the function of the cell is altered.
Is rheumatic fever type 2 hypersensitivity?
It is believed to be caused by antibody cross-reactivity. This cross-reactivity is a Type II hypersensitivity reaction and is termed molecular mimicry.
Which of the following is an example of a type 2 hypersensitivity?
An example of complement dependent type II hypersensitivity is an acute haemolytic transfusion reaction following transfusion of ABO incompatible blood.
Why does Type 2 hypersensitivity occur?
A type II hypersensitivity is said to occur when damage to the host tissues is caused by cellular lysis induced by the direct binding of antibody to cell surface antigens. While the antibodies involved in type I HS are of the IgE isotype, those involved in type II HS reactions are mainly of the IgM or IgG isotype.
What is the difference between Type 2 and Type 3 hypersensitivity?
Type 2 hypersensitivity reactions may occur in response to host cells (i.e. autoimmune) or to non-self cells, as occurs in blood transfusion reactions. Type 2 is distinguished from Type 3 by the location of the antigens – in Type 2, the antigens are cell bound, whereas in Type 3 the antigens are soluble.
What is Type 3 hypersensitivity reaction?
In type III hypersensitivity reaction, an abnormal immune response is mediated by the formation of antigen-antibody aggregates called “immune complexes.” They can precipitate in various tissues such as skin, joints, vessels, or glomeruli, and trigger the classical complement pathway.
Is rheumatic fever type 2 or 3 hypersensitivity?
The similarity between antigens of Streptococcus pyogenes and multiple cardiac proteins can cause a life-threatening type II hypersensitivity reaction. Usually, self reactive B cells remain anergic in the periphery without T cell co-stimulation.
What is Type 2 hypersensitivity reaction?
Type II hypersensitivity reaction refers to an antibody-mediated immune reaction in which antibodies (IgG or IgM) are directed against cellular or extracellular matrix antigens with the resultant cellular destruction, functional loss, or damage to tissues.