Classification of immunoglobulins

Question 1

How many classes

Answer 1

5 classes
Namely:
IgG
IgA
IgM
IgE
IgD

Question 2

IgG

Answer 2

Structure; Monomer
❑Produced by Plasma cells
❑Location;Blood,Lymph,intestine
❑Half-life in serum;23days
❑Major immunoglobulin;70–80% in serum.
❑Produced in response to most of bacteria and virus.
❑It binds to macrophages and Neutrophills and
promotes phagocytosis.
❑Placental transfer,protects fetus and newborns.

Question 3

IgA

Answer 3

❑Structure;Dimer
❑Location;secretions(tears,saliva,intestine,milk),
blood,lymph
❑Present in 15–20% of total serum;half-life;6days
❑Called as “Secretory IgA” since it is present in
❑some secretions like Milk,Saliva and Colostrum( 1st milk produced by body during pregnancy) etc.
❑S IgA provides defense against virus and bacteria.
❑Deficiency of IgA causes infection in sinus and
Respiratory tract
❑No placental transfer

Question 4

Ig M

Answer 4

❑Structure;Pentamer
❑Location;Blood,lymph,Bcell surface(monomer)
❑5–10%present in serum;Half-life;fivedays
❑1st immunoglobulin, synthesized by cells
on the entry of antigens into the host.
❑Also called first line of defense.
❑Effective against microbes and agglutinating antigens
❑No placental transfer but it’s the only Immunoglobulin the
neonates normally synthesize.

Question 5

Ig E

Answer 5

❑Structure;Monomer
❑Present in very small amount in blood(0.002%)
❑Location;found on surface membrane of the
basophills and mast cells.
❑Half-life;2days
❑No placental transfer
❑It protects the host against parasites and allergic reactions
such as Hay Fever and Asthma,and possibly lysis of worms

Question 6

Ig D

Answer 6

❑Structure;Monomer
❑Location;B-cell surface,blood and lymph
❑Half-lifeinserum;3days
❑<than1% of immunoglobulin is IgD in serum.
❑Major component of surface membrane of many B–cells.
❑In serum function is unknown but on Bcell surface it
initiates immune responses