Hypersensitivity type II is an antibody-mediated immune response that causes damage to host cells rather than providing protection. It occurs when antibodies bind to antigens on cell surfaces, activating the complement system and promoting antibody-dependent cell-mediated cytotoxicity. This leads to cell lysis or dysfunction. Diseases associated with type II hypersensitivity include autoimmune hemolytic anemia, autoimmune thrombocytopenia, transfusion reactions, hemolytic disease of the newborn, pemphigus vulgaris, and Goodpasture syndrome. Diagnosis involves tests like direct and indirect Coombs tests. Treatment focuses on controlling symptoms using steroids, intravenous immunoglobulin, or plasmapheresis to remove antibodies.

1. HYPERSESITIVITY II
GROUP 8

2. OUTLINE
• What Is Hypersensitivity II
• Antibodies Involved
• Mechanism Of Damage
• Diseases Associated
• Risk Factors
• Diagnosis And Treatment

3. HYPERSENSITIVITY II (ANTIBODY-MEDIATED
CYTOTOXICITY)
• The immune system provides protection against pathogens, infections and
diseases.
o Distinguish between self and non-self
• But sometimes;
o Immune mechanisms cause damage instead of providing protection
• This happens when……
o Immune system overreacts to certain foreign antigens
o Or mechanism of self-tolerance fails

4. HYPERSENSITIVITY II (ANTIBODY-MEDIATED
CYTOTOXICITY)
• Hyper (GK. “huper”) means over, above.
• Sensitivity : Ability to detect and respond to slight changes and signals
• Any immune response that is excessively above normal
o Inappropriate immune response , result in host damage.
• Type I, II, and II occurs based on;
o Effector mechanisms involved
o Time of onset

5. TYPE II (ANTIBODY-MEDIATED CYTOTOXICITY)
• Time of onset 5-8 hours
• Mediated by antibodies directed against antigens present on cell surfaces
o Antibodies IgG and IgM are involved
o The isotype antibodies bind to cell surface antigens
• Activation of complement
• Binding Fc receptors on Tc cells promoting antibody dependent cell-
mediated cytotoxicity (ADCC)

6. MECHANISMS OF DAMAGE
• Complement activation
A. Opsonization or Opsonized phagocytosis
B. Cell lysis by MAC complex
• Antibody dependent cell-mediated cytotoxicity
• Antibody-mediated cellular dysfunction

7. MECHANISM OF DAMAGE

8. MECHANISM OF DAMAGE
• Diseases associated;
1. Autoimmune hemolytic anemia (RBC’s destroyed before lifespan is over)
2. Autoimmune thrombocytopenia (Low platelets level leads to bleeding)
NON AUTOIMMUNE TYPE (ISOIMMUNE)
1. Transfusion reactions (ABO incompatibility)
2. Hemolytic disease of the newborn (HDN) – erythroblastosis fetalis
3. Graft rejection

12. MECHANISM OF DAMAGE
• Diseases associated;
1. Pemphigus vulgaris (Blistering skin and mucous membranes)
2. Goodpasture syndrome (Antibodies attack basement membrane)

13. MECHANISM OF DAMAGE
• Antibody dependent cell-mediated cytotoxicity;
• Chemoattractant or chemotactic
factors (C4a, C3a, C5a)
• Attracts phagocytic cells (NK cells,
neutrophils, monocytes etc.)

14. MECHANISM OF DAMAGE
• Antibody-mediated cellular dysfunction;
Grave’s disease Myasthenia gravis

15. RISK FACTORS
• Depending on manifestation of different type II hypersensitivity
diseases, there are different risk factors as well.
• Some diseases are more common in women such as Grave’s disease.
• However, disease such as Goodpasture’s syndrome are more common in
men.
• Also ethnic differences do occur in type II hypersensitivity diseases.

16. DIAGNOSIS
• Depending on the different type of diseases, some general investigations
may be necessary.
• Basic investigation may include looking at the:
• Blood function, liver function, and kidney function
• Direct and indirect Coombs test can be used.

17. TREATMENT
• There is no cure for this diseases, the treatment aims at symptom control
only.
• Because the pathogenesis of this disease antibody in origin, a lot of
treatment options are aimed at that.
• Steroids: These drugs include prednisolone, dexamethasone, etc.
There are other treatment methods all aiming at altering the bodies immune
response, this include;
• Instagram infusion: This is infusing the body with antibodies.
• Plasmapheresis: This removing the blood autoantibodies

18. REFERENCES:
• Kuby – Immunology
• Janeway – Immunology
• Braunwald E et al. Harrison’s principles of internal medicine.
15th ed. New York; McGraw-Hill; 2001.
• Cotran, Kumar, Collins. Robbins Pathologic Basis of Disease.
6th ed. WB Saunders Company. New York. 1999.
• eMedicine: Graves Disease [online]. 2004. [Cited 2005
October 9th]. Available from:
http://www.emedicine.com/ped/topic899.htm