TYPES OF IMMUNOGLOBULINS

IgG

IgA

IgM

IgD

IgE

5 TYPES OF IMMUNOGLOBULINS

IgG

Predominant Ig among humans comprising 75-80% of the total Ig pool

IgG

Equally distributed in the different fluid compartments with detectable amounts in CSF and urine

IgG

Readily diffusible

IgG

Predominant antibody in anamnestic response

6-9 months

Maternal IgG is actively and selectively transferred across the placenta to the fetus and imparts passive protection to the newborn for how many months?

Ig1, Ig2, Ig3, Ig4

IgG 4 subclasses:

Ig1, Ig4

2 disulfide bonds

Ig2

4 disulfide bonds

Ig3

15 disulfide bonds

Ig1

Best for neutralization, to cross the placenta, has highest concentration

Ig2

Cannot cross the placenta

Ig3

Best to fix complement with large hinge region and large interchain of disulfide bond

Ig4

Cannot fix the complement

IgM

The largest of the immunoglobulin molecule, accounting for 5-10% of the total immunoglobulin pool

IgM

The earliest antibody to appear in the primary immune response but it doesn’t persist for long

IgM

Primitive Antibody Macroglobulin

IgM

Star shaped in the free state; crab-like in antigen-antibody reaction

IgM

Maternal IgM does not cross the placenta

IgM

Seen in intravascular hemolysis

IgM

A powerful agglutinator of particulate antigen

IgM

Reacts best at cold temperature

IgM

Held together by J or joining chains

IgM

Confined to the intravascular pool due to its large size

10

IgM number of valence/antigen binding sites

IgA

Represent 15-20% of human serum Ig pool

IgA

Found in serum in small amount but predominant in seromucous secretions of the respiratory tract, genitourinary tract and GI tracts

IgA

Found in saliva, sweat, tears, colostrum and breastmilk

Serum IgA (IgA1)

Secretory IgA

Secretory component

Forms of IgA:

Serum IgA (IgA1)

Can agglutinate motile infectious agents thus promoting their phagocytosis but they cannot activate the complement system

Secretory IgA

It is known as the “antiseptic paint” of mucous membranes

Secretory IgA

Can activate the bacteriolytic activity through the alternate pathway of complement system and only the presence of lysozyme

Secretory component

Protects IgA from digestion by proteolytic enzymes and act to facilitate transport of IgA to mucosal surfaces

IgD

Heat labile immunoglobulin

IgD

Accounts for less than 1% of the total serum Ig

IgD

Anti-idiotypic Antibody

IgD

Precise biological action is not known but it may play a role in antigen-triggered lymphocyte differentiation

IgE

Heat labile immunoglobulin, least abundant Ig in the serum accounting for only 0.002% of the total serum Ig

IgE

Synthesized locally by plasma cell present I the mucous membrane of the GI and respiratory tracts

IgE

It is unable to fix the complement via the classical pathway

IgE

It is homocystotropic due to its affinity for cells of the host species, particularly for tissue mast cells and blood basophils

IgE

Associated with immediate hypersensitivity reactions & with immunity to certain helminthic parasites

REAGINIC ANTIBODY/NUISANCE ANTIBODY

IgE is also known as