Slides about immunology and hypersensitivity

1. TYPE II
HYPERSENSITIVITY

2. Type II hypersensitivity
• Is antibody(IgM or IgG) mediated
hypersensitivity reaction.
Antibody is directed against antigens that
are fixed or instrinsic to the tissue to which
the reaction occurs.
Type II Hypersensitivity is subdivided into
three types.

3. 1.Target cell depletion or
destruction without inflammation
• Classic example of this type II
hypersensitivity is Autoimmune hemolytic
anemia warm type.
• IgG antibody binds to RBCs and its fc
portion is activated binding to the
macrophage to phagocytose RBCs .

4. Cont..
Another examples are ,
ABO incompatibility
autoimmune neutropenia
autoimmune thrombocytopenia and
erythroblastosis fetalis.
 Antibody activates complement system and
Membrane attack complex lysis the
cell(MAC).

5. Erythroblastosis fetalis,Rh negative mother
develops antibodies against Rh positive fetus
which crosses the the placenta destroying fetal
RBCs.
Rhogam antibody is injected to the mother 24-
48 hours after 1st delivery. It will bind to the fetal
RBCs that enter the mother's circulation and
facilitate the clearance of them before B cell
activation.

7. Cont..
Antibody Dependent cell mediated
cytotoxicity(ADCC).
Antibody bind to target cell and activates
cytotoxic T Cell which releases granzymes
and perforins to lyse the target cell.

8. 2.Complement or Fc receptor
mediated inflammation
In Glomerulonephritis,antibody is binds to
collagen in glomerular basement membrane
and activates complement system , released
C3a or C5a acts as chemoattractant and
Mast cell stimulator resulting inflammatory
response.
This type of Hypersensitivity type II occurs
in good pasture syndrome

9. 3.Antibody mediated cell
dysfunction
In this there no cell destruction or
Inflammation.
In Graves disease,Autoantibodies bind to the
TSH receptors on thyroid follicles and excess
T3 and T4 is secreted leading to
Hyperthyroidism.

10. Cont...
Another example is Myastenia
gravis,autoantibodies bind to the cholinergic
receptors on the muscle cell preventing
acetylcholine from binding to the receptor in
the neuromuscumar junction.
Person cannot move his muscles and
extreme fatigibility develops.