Kindly find the brief description about the antibodies Immunoglobulins.

2. Antibodies – Immunoglobulins
• Towards the end of 18th century, it was demonstrated that after injection of an
antigen into an animal ,certain substances called antibodies appeared in the blood
and tissue fluids ,which reacted with antigen specifically and in some observable
manner .Depending on the reaction with antigen, these antibodies were called
agglutinins, precipitins, etc. Sera having high antibody levels following infection
or immunisation are called immune sera.

3. Fractionation of immune sera by half saturation with amm. sulphate
separated serum proteins into:
A) soluble albumins and
B) insoluble globulins .
Globulins can be separated into a) water soluble pseudo globulins and b)
insoluble euglobulins.
Most antibodies were found to be euglobulins.

4. Tiselius(1937) separated serum proteins into albumins, alpha ,beta , and gamma
gloublins. Depending on their electrophoretic motility. Antibodies were shown
to be associated with gamma gloublins.
Various terms were used to describe antibodies. Hence WHO endorsed the term
Immunoglobulins - defined as proteins of animal origin, endowed with known
antibodies activity and also included certain other proteins with similar chemical
structures.(Abnormal proteins found in multiple myeloma, macroglobulinemia ,
cryoglobulinemia)

5. Immunoglobulins are synthesized by plasma cells.
Constitute 20-25% of total serum proteins.
Based on physiochemical and antigenic properties, five classes of Ig have
been recognised. IgG, IgA, IgM, IgD, IgE. Depending on structure of
heavy chains.

6. Electrophoresis of serum
• Buffer 100 ml 2 gms – Difco / noble agar powder heat. Property of agar
melts / dissolves at 95°C solidifies at 42°C.
• Pour on glass slide
• Agar solidifies & forms a transparent layer
• Electrophoresis apparatus 30 m.v. – About 2 hours. Bromothymole blue-
Albumin.

7. Structure of Ig molecule
• Glycoprotein ,each molecule has 2 pairs of polypeptide chains
• 2 larger chains-Heavy chains
• 2 smaller chains-Light chains
• Heavy chains – MW 50,000-Amino acids 400 structurally& antigenically
different Heavy chains Ig G(gamma),IgA(alpha),Ig M(mu),Ig D(delta),Ig
E(Epsilon).

8. • Light chains – MW 25,000-Amino acids 200.Two types-Kappa & Lamda
(Korngold & lapori) only one type present in Ig mol, never both K:L ratio = 2:1
Effect of enzymatic digestion:
L Chains = 214 AA residues
107AA each in the constant & variable region.
H Chains=
Variable = 1/5th of chain.

9. Basic structure

12. Ig class ‘H’ chain
Ig G Gamma
Ig A Alpha
Ig M Mu
Ig D Delta
Ig E Epsilon

14. Comparison of properties
Ig & no. of subclasses IgG (4) IgA (2) IgM (2) IgD (2) IgE
Serum conc. Mg/ml 12 (80%) 2 (10-13%) 1.2 (5-8%) 0.03 0.00004
Mol. wt. 150,000 160,000 900,000 180,000 190,000
Sed. coefficient 7S 7S 19S 7S 8S
Intravascular Distribution % 45 42 80 75 50
No. of Ig mol Monomer Dimer Pentamer Monomer Monomer
Valency 2 4 10 2 2
Daily prod mg/kg 34 24 3.3 0.4 0.0023
Half life (days) 23 6 5 2.8 2.3
Comple. Fixation
Classical
Alternate
++
-
-
+
+++
-
-
-
-
-

15. Ig & no. of Sc. IgG (4) IgA (2) IgM (2) IgD (2) IgE
Placental transport + - - - -
Presence in milk + + - - -
Selective secretion by
seromucus gland
- + - - -
Heat stability at 56 ºC + + + + -
Main function Protect body
fluids
Protects body
surfaces
Protects blood
stream
Recognition
receptor forAg
Takes part in
type 1
hypersensitivity
rect.
Note for IgA -Two form
7S – present in serum monomer
11S – present on mucosal surfaces & secretions of sero mucus glands Dimer- I chain
joined by J chain.
Secratory IgA is produced by mucosal / glandular epithelium.

16. Ig M
1) First to appear(6-7 days after infection.
2)Persists for short times(4-6wks)Hence presence of IgM antibodies indicates
recent/active infection.
3) Lower levels in necessary ab response as compared to IgG.
4) Can be synthesized by foetus from 20 wks of age. Its presence in total blood

17. Appearance of antibodies
Ig M IgG
1) First to appear(6-7 days after infection. 1)Appears later than IgM ( 2 wks after infection)
2) Persists for short times(4-6wks) Hence
presence of IgM antibodies indicates
recent/active infection.
2) Persists for longer longer period. Its presence indicates
earlier, previous infection
3) Lower levels in necessary ab response as
compared to IgG.
3) Higher levels achieved in secondary immune response.
4) Can be synthesized by foetus from 20 wks
of age. Its presence in total blood

18. Function
IgG IgA IgM
body fluids equal
distribution
intravascular & extra
vascular.
Mucosal surfaces present in
mucosa of Resp./GI tract,
Genito urinary tract. Also in
milk ,colostrums ,saliva
,tears.
Blood stream
Mainly present intravascular.
Large molecule/ Millioner
molecules.
Binds to micro
organism & enhance
phagocytosis
Forms antibody paste on
mucosa
Many natural Ab to micro org. are
IgM in nature.
Takes part in
neutralisation of
toxins, viruses,
precipitation & CF
rections.
Inhabit adhesion of micro
org to mucosal cells.
Promates phagocytosis
intracellular destru. of
organisms.
More effective than IgG
20 times for Bact. Agglu.
100 times for bactericidal
500 times for Opsonisation
1000 times for Hemolysis.

19. IgD- Structure similar to Ig G.
t ½=3 days, 3 mg/100 ml – intravascular
Serves as recognition receptor for antigens Ig D and Ig M are present on
surface of unstimulated B lymphocytes.
Combination of antigen with cell membrane bound Ig D result in specific
stilulation of E cells
Effect-1)Activation of B cells ,cloning, and antibody formation.
2)Suppression.

20. IgE- Structure similar to Ig G (Discovered by Ishizaka in 1966)
Important properties and functions of Ig E-
1. Heat labile- inactivated in 1 hr at 56°C.
2. Has affinity for surface tissue cells(particularly mast cells) of same
species(Homocytotrophic antibodies) Human Ig E - Human cells.
3. Mediates Fraunitz - Kustner rection
4. Susceptible to mercapto ethanol

21. 5. Does not pass through placenta or fix complement
6. Normal serum conc is very low(few nano grams/ml)but high levels are seen in
type 1hypersensitivity/allergic reactions like-asthma, hay fever and eczema.
7. Responsible for anaphylactic hypersensitivity reaction.
8. Chiefly produced in lining of respiratory and intestinal tracts. Relation with Ig A-
Mucosa of resp/int tract contains Ig A Ab producing p cells & Ig A. Most allergens
are dealt with by Ig A and do not come in contact with Ig E producing cells.

22. However in IgA deficiencty, antigen causes direct, prolonged stimulation of IgE
producing cells. Over production of IgE – allergic manifestations.
9. Cannot be estimated by routine methods serum conc. is 0.00004 mg / ml.
measured by RAST-Radio-allergo-sorbent-test Elisa or Passive agglutination
test.

23. Abnormal Immunoglobulins
Abnormal proteins, having structure similar to Ig, but no antibody activity.
Bence Jones proteins - Found in urine of patients with multiplemyeloma &
waldenstroms macroglobulinemia
Property: While heating urine samples,BJ proteins coagulate at 50°C&
redissolve at70°C.These are the light chains of Ig -Either K or L chains.

24. Property
1. Multiple myeloma- malignant condition affection plasma cells which
produce IgG, IgA, IgD, IgE.
2. Waldestroms macroglobulinemia- malignant condition IgM producing
plasma cells.Thus M proteins & BJ proteins are produced.
3. Heavy chain disease- overproduction of Fc parts of Heavy chains.

25. 4. Eryoglobulinemia- When serum is cooled–Formation of gel
IgG/IgM.
When serum is warmed– gel redissolves.
Found in myelomas, macroglobulinemias, auto
immune diseases.

26. Prausnitz-kustner reaction
Allergen Interaction with IgE on the Surface of Mast Cells triggers the Release of
Inflammatory Mediators

27. Prausnitz-kustner reaction
• Kustner had atopic hypersen. to cooked fish
• His serum was injected intradermally in fore arm of prausnity
• 24hrs later small amt of cooked fish susp.is injected ID at same site in
praunity
• Result-wheal & flare reaction within few minutes

28. IDIOTYPE SPECIFICITY SPECSFICITIES
ISOTYPIC SPECIFICITY
ALLOTYPIC SPECIFICITY
 Idiotype = Sum total of
idiotype on an Ig molecule.
 Idiotype = Sp.Ag
detetmination on the paratope.
Ag. Specificities which
distinguish between diff.
Classes & subclasses of
Igs in all individuals of a
given species.
Antigenic specificities which
distinguish Igs of the same
class, between diff. groups of
individuals in same species.