1. IMMUNOLOGY
Immunoglobulin

2. immunoglobulin Introduction the basic structure of immunoglobulins
Fuction of immunoglobulins
the structures and properties of immunoglobulin classes
Monoclonal antibody

3. Introduction immunoglobulin
Immunoglobulins (Ig) - Glycoprotein molecules which are produced by plasma cells in response to an immunogen and which function as antibodies. The immunoglobulins derive their name from the finding that when antibody-containing serum is place in an electrical field the antibodies, which were responsible for immunity, migrated with the globular proteins - secreted Ig(sIg) ; membrane Ig(mIg)

4. immunoglobulin
Introduction

5. Introduction immunoglobulin
Antibody(Ab) - Serum protein formed in response to immunization; antibodies are generally defined in terms of their specific binding to the immunizing antigen.

6. basic structure of the immunoglobulins

7. basic structure of the immunoglobulins
1.Heavy Chain and Light Chain heavy chain (H chain) 50-75Kd aa isotype:IgM,IgD,IgA,IgE,IgG H chain: μ δ α ε γ light chain (L chain) 25Kd 214aa classes of L chain: κ λ

8. basic structure of the immunoglobulins
2.variable region and constant region variable region(V region) Light Chain - VL (110 aa) Heavy Chain - VH (110 aa) HRV(hypervariable region) CDR(complementarity-determining region) FR(framework region)

9. basic structure of the immunoglobulins
CDR binds with epitope of antigen

10. basic structure of the immunoglobulins
2.variable region and constant region constant region(C region) Light Chain - CL (110 aa) Heavy Chain - CH ( aa) CH1, CH2, CH3,( CH4)

11. basic structure of the immunoglobulins
3. Hinge Region
- between the CH1 and CH2 region of the H chain
- be made of cysteine and proline residues
cysteine:be involved in formation of interchain
disulfide bonds
proline residues:prevent folding in a globular
structure
flexibility: allow the two Fab arms to open;
close to accommodate binding to epitope;
be cleaved by proteases.
- IgM and IgE have no hinge region

12. Domains of immunoglobulin
Domains - 3D images of the immunoglobulin molecule shows that it is not straight as depicted in Figure. Rather, it is folded into globular regions each of which contains an intra-chain disulfide bond. These regions are called domains. 1. Light Chain Domains - VL and CL 2. Heavy Chain Domains - VH, CH1,CH2, CH3 (or CH4)

13. Domains of immunoglobulin

14. immunoglobulin
Domains of the Ig

15. immunoglobulin

16. Immunoglobulin fragments

17. J chain and SP immunoglobulin
Joining chain -J chain a ploypeptide chain Join the units together

18. immunoglobulin
J chain and SP
Secretory piece -SP,SC

19. Function of immunoglobulins
Functions of V regions
- recognition and binding to antigen
- HVR (CDR)
- neutralization of toxins; immobilization
of microorganisms; neutralization of
viral activity

20. 1. Activation of complement: IgM, IgG1,3; IgA
immunoglobulin
Function of C regions (Fc portion)
1. Activation of complement: IgM,
IgG1,3; IgA
2. Binding to Fc receptor of cell
opsonization, enhancement of Ag uptake by DC and M
ADCC
Participation in type I hypersensitivity
3. Passage through the placenta (IgG)
and mucosa (sIgA)

21. Opsonization of antibody
immunoglobulin
Opsonization of antibody

22. Antibody-dependent cell-mediated cytotoxicity (ADCC)
immunoglobulin
Antibody-dependent cell-mediated cytotoxicity (ADCC)

23. IgG immunoglobulin IgG is the major Ig in serum - 75% of serum Ig
IgG is the major Ig in extra vascular spaces
c) Fixes complement - Not all subclasses fix equally
well; IgG4 does not fix complement
d) Binding to cells - Macrophages, monocytes, PMN's and some lymphocytes have Fc receptors for the Fc region of IgG.

24. IgM immunoglobulin a) IgM is the 3rd most common serum Ig.
b) IgM is the first Ig to be made by the fetus and the first Ig to be made by a virgin B cells when it is stimulated by antigen.
c) As a consequence of its pentameric structure, IgM is a good complement fixing Ig. Thus, IgM antibodies are very efficient in leading to the lysis of microorganisms
d) As a consequence of its structure, IgM is also a good agglutinating Ig .
e) IgM binds to some cells via Fc receptors.

25. IgA a) IgA is the 2nd most common serum Ig.
immunoglobulin
IgA
a) IgA is the 2nd most common serum Ig.
b) IgA is the major class of Ig in secretions –
tears, saliva, colostrum, mucus. Since it is
found in secretions secretory IgA is
important in local (mucosal) immunity.
c) Normally IgA does not fix complement,
unless aggregated.
d) IgA can binding to some cells - PMN's and
some lymphocytes.

26. immunoglobulin
IgA

27. IgD a) IgD is found in low levels in serum; its role
immunoglobulin
IgD
a) IgD is found in low levels in serum; its role
in serum uncertain.
b) IgD is primarily found on B cell surfaces
where it functions as a receptor for
antigen. IgD on the surface of B cells has
extra amino acids at C-terminal end for
anchoring to the membrane. It also
associates with the Ig-alpha and Ig-beta
chains.
c) IgD does not bind complement.

28. IgE IgE is the least common serum Ig
immunoglobulin
IgE
IgE is the least common serum Ig
since it binds very tightly to Fc receptors on basophils and mast cells even before interacting with antigen.
b) Involved in allergic reactions
c) IgE also plays a role in parasitic
helminth diseases
d) IgE does not fix complement

29. immunoglobulin
Monoclonal antibody