Talk 3

Antibody

Structures of Five Classes of Igs

Classes and Subclasses of Igs from Human and Animals

Species

Horse

Cattle

Sheep

Pig

Dog

Cat

Chicken

Mouse

Human

IgG

Ga, Gb, Gc, G(B), G(T)a, G(T)b

G1, G2(G2a,G2b)

G1(G1a?), G2, G3

G1, G2a, G2b, G3, G4

G1, G2, G3, G4

G1, G2, G3, (G4?)

G1, (G2a?), (G3?)

G1, G2a, G2b, G3

G1, G2, G3, G4

IgA

A

A

A1, A2

A1, A2

A

A1, A2

A

A1, A2

A1, A2

IgM

M

M

M

M

M

M

M

M

M

IgE

E

E

E

E

E1,E2

E

E

E

E

IgD

?

-

-

-

D

?

?

D

D

Antibody Structure

Polymeric Structure of Antibodies

Isotypes of Immunoglobulins

IgG IgA

The genes for isotypic variants are present in all healthy members of a species. For examples, the genes forγ1, γ2,γ3,γ4, , α1,α2, δ, , and c

hains are all present in the human genome and therefore isotypes.

Allotypes of Immunoglobulins

IgG IgG

Genetic variation between individuals within a species, involving different alleles at a given locus. Allotypes occur mostly as variants of H chain C region.

Idiotypes of Immunoglobulins

IgG IgG

Variation in the variable domain, particularly in the hypervariable regions, produces idiotypes, which determine the binding specificity of the antigen-binding site. Idiotypes are usually specific for individual B-cell clone (private idiotypes ), but are sometimes shared between different B-cell clones (public, cross-reactin

g or recurrent idiotypes)

Properties of Human Igs

Functions of Antibody(Direct Neutralization)

Functions of Antibody(opsonization)

Functions of Antibody(ADCC Killing)

Functions of Antibody(complement activation)