The document provides an overview of immunoglobulins, including their structure, types, and functions. It details the composition of antibodies, highlighting the differences between various immunoglobulin classes such as IgG, IgM, IgA, IgD, and IgE. Additionally, it discusses the roles these antibodies play in the immune system, including antigen binding, complement activation, and their ability to cross the placenta.

1. MUHAMMAD ASIF ZEB
LECTURER HEMATOLOGY
IPMS
IMMUNOGLOBULIN

2. IMMUNOGLOBULINS
Immune
serum
Ag-adsorbed
serum
α1 α2 β γ
+ -
albumin
globulins
Mobility
Amountofprotein
Igs are glycoproteins, produced in response to an immunogen by plasma
cells

3. STRUCTURE OF ANTIBODIES
Simply Y shape structure
Composed of 2 identical heavy polypeptide chains and 2 identical
light chain.
Heavy chain means have high molecular weight i.e 50,000-77,000d
and composed of 450 amino acid.
There are five chain classed of heavy chain i.e mu(u), gamma(r),
alpha(a), delta(&) and epsilon(e)
Light chain are smaller having molecular weight 25ooo and
composed of 212 amino acid
Light chain may be further divide into either kappa or lambda.
Immunoglobulin may contain either kappa or lambda but not both

4. CONTI
Light and heavy chain are join to each other by disulfid bond
The light and heavy chain is composed of constant and
variable region.
The first 110-120 amino acid of the light and heavy region
form variable sequence and thought to antigen binding site.
The constant region is further divide into C1H,C2H and C3h
each have their own function.
In the medal of antibody a region called hinge region which
gives feasibility to antibody.

5. IMMUNOGLOBULIN FRAGMENTS:
STRUCTURE/FUNCTION RELATIONSHIPS
Ag Binding
Complement Binding Site
Placental Transfer
Binding to Fc
Receptors

6. HUMAN IMMUNOGLOBULIN CLASSES
Despite similarities, Abs are divided (size, charge,
solubility) into distinct classes and subclasses
• IgG - Gamma (γ) heavy chains
• IgM - Mu (µ) heavy chains
• IgA - Alpha (α) heavy chains
• IgD - Delta (δ) heavy chains
• IgE - Epsilon (ε) heavy chains

7. IGG
• Structure
• Monomer
IgG1, IgG2 and IgG4 IgG3

8. IGG
• Structure
• Properties
• Major serum Ig about 85% of imunoglobulin
• Monomeric structure
• Can cross placenta as have receptor on placenta
• Can Fixes complement (± IgG4)
• Opsonin antibodies and help in phagocytosis.
• Incomplete antibodies
• Best react at 37 c

9. • IgG Subclass
• IgG1 - Gamma 1 (γ1) heavy chains have 2 inter chain
disulfide bond
• IgG2 - Gamma 2 (γ2) heavy chains have 4
• IgG3 - Gamma 3 (γ3) heavy chains have 11
• IgG4 - Gamma 4 (γ4) heavy chains have 2
Ig3 have highest ability to activate complement followed by
Ig1 and then Ig2 while Ig4 cant

10. IGM
• Structure
• Pentamer , so it can
bind 10 antigen at a
time.
• Extra domain (CH4)
• Also contain J chain
which form disulfiod
bond with hinge region
• Diameter 300 Angstrom
• Length of monomer is
100 A
• 25-30 A width.
Cµ4
J Chain

11. IGM
•Properties
• 3rd highest serum Ig
First Ig made by fetus and B cells
• It Fixes complement
• Can not cross placenta
• Complete antibodies
• Usual temp 20c but best temperature is 4c
–Agglutinating antibody

12. Fixation of C1 by IgG and IgM Abs
C1r C1s
C1q
C1r C1s
C1q
No activation Activation

13. IGA
• Structure
• In Serum 90% occurs as monomer and 10% as
dimer.
• In Secretions (sIgA) 90% occurs as Dimer and
10% as monomer.
• SigA Have J chain in its structure
Also have Secretory component.
J ChainSecretory Piece

14. IGA
Properties
• It is 2nd highest serum Ig
• Major secretory Ig (Mucosal or Local Immunity)
• Tears, saliva, gastric and pulmonary secretions and server as first
lie of defense against microorganism invasion.
• Does not fix complement
• Cannt cross placenta
• Temp 37c
•IgA subtype
• IgA1 - Alpha 1 (α1) heavy chains
• IgA2 - Alpha 2 (α2) heavy chains

15. IGD
• Structure
• Monomer
Tail Piece

16. IGD
• Structure
• Properties
• 4th highest serum Ig
• B cell surface Ig
• Does not bind complement
• Function is unknown but may important as lymphocytic
differentiation.

17. IGE
• Structure
• Monomer
• Extra domain (CH4)
Cε4

18. IGE
• Structure
• Properties
• Least common serum Ig
• Binds to basophils and mast cells (Does not require Ag binding)
• Allergic reactions
• Binds to Fc receptor on eosinophils
• Does not fix complement

19. Abs: Molecules for immune effector system
a. Activate C’ – lysis & phagocytosis of microbes
b. Binds to Ag – enhance phagocytosis
c. Recognition of target
d. Stimulates degranulation of mast cells & release mediators
e. Cross placental barrier