Hypersensitivity type 2

Hypersensitivity type 2 immunology

1. UNIVERSITY OF EDUCATION LOWER MALL LAHORE . Subject immunology .Topic Hypersensitivity type 2

2. CONTENTS Definition .Types II .ADCC Complement complex .Opsonization Example References

3. Type II hypersensitivity reaction involves antibody mediated destruction of cells. It is also known as cytotoxic reaction. . In thi s hypersensitivity reaction, specific antibody (IgG or IgM) bound to cell surface antigen and destroy the cell.

4. They are following mechanism involes 1-Co mplement mediated cell lysis 2-Antib ody dependent cell mediated cytotoxicity (ADCC) 3- Opsonization

5. Compplement mediated lysis of cell ●when antibody binds to antigen (microorganism or RBC) they form Ag-ab complex. ● Ag-a b complex can activate complement system by different mechanism . .when complement activated on surface of cell RBC then lysis of cell.

6. Antibody dependent cell mediated cytotoxicity (ADCC): ● Antib ody binds with antigen by its Fab portion. However Fc region of antibody has receptor on cytotoxic cells. ● Most cytotoxic cells contain storage of hydrolytic enzymes

7. ● Here antibody itself does not kill or destroy cell but rather mediate killing by presenting antigen to cytotoxic cell ● . Similarly cytotoxic cell depends upon antibody to bind antigen. So this mechanism is known as A ntibody dependent cell mediated cytotoxicity.

8. Opsonization ● When antigen enters into host body, antibodies are produced. ● phagocytic cells such macrophages,monocytes have aceptor attach fc region of antibody. ● That binding antigene with antibody then increase phagocytosis is called opsonization

9. Example Blood transfusion Introduced blood from outside of body. .when person transfered wrong blood the antigene present on blood recongized by antibody on blood of person. Drug reaction ..Drug like penicillin absorb on RBC surface that form complex .That bind with drug on RBC then lysis of cell.