2. Objectives;
Define secretary IgA
Describe structure & functions of IgM
Compare the antigenic receptor of B
lymphocyte
Assess the role of IgE in Atopy
Distinguish between Isotype, Allotype &
Idiotype
Explain Anti-idiotype Ab
List the characteristic of specific
Immune response
Compare between primary &
secondary Immune Response

3. IgA Constitute 15% of total serum Ig
Main Ig in the external secretions as saliva tears breast milk
Subdivided into IgA1 & IgA2 subclasses
It has 2 forms ;
1-Monomeric in the blood
2- dimeric in the external secretions

4. Dimeric IgA secretary IgA
IgA synthesized by plasma cell as monomeric one in the submucosa which will be combine with another monomeric IgA by a polypeptide J chain to form dimeric IgA this will be protected by a secretary piece from the secretary epithelium to form the
secretary IgA

6. Secretory piece( SP): IgA . Produced by mucosa epithelial cells
. Secretory IgA (sIgA)
. Functions: protect sIgA, resist proteolysis in extra secretory liquid.
J chain
IgA SP

7. Ⅲ. IgA 1. Two types Serum type ：monomer 2. Two subclasses：IgA1，IgA2
Secretary type（sIgA）: dimer
2. Two subclasses：IgA1，IgA2

8. Functions of secretary IgA
Activation of the complement through the alternative pathway Blocking & Neutrilization opsonization

9. IgM lymphocytes as antigen Receptor together with IgD
Constitute 10% of total serum Ig
Its molecular weight (Heavy)
It has 2 forms
1-Monomeric form on the surface of B
lymphocytes as antigen Receptor together with IgD
2-pentameric IgM 5 monomeric connected
by J chain

10. Pentameric IgM

11. It is the main Ig in the primary immune response
IgM has no hinge region replaced by an additional domiain(CH2)---CH3,CH4
Pentameric IgM has 10 FAB so it is the most agglutinating & complement fixing Ab
It is the main Ig in the primary immune response
It is the 1st Ig synthetized by the fetus

13. IgD Very low concentration in the blood less than 1%
Short half life 2-3 days
Present on the surface of B lymphocyte together with monomeric IgM as a surface antigen receptor of B lymphocyte
Immature B cell only IgM on its surface
Mature B cell IgM+IgD on its surface

14. IgE 0.002 % of serum Ig ( detection by Elisa)
In atopic patient the level increase by handreds
IgE also called Reagenic or homocytotropic Ab because of its ability of binding to FC receptors on the surface of Mast cells & basophiles

15. FceRI
degranulation
IgE
allergen
inflammation

16. Functions of IgE Triggering an acute inflammatory reaction
Has the ability to bind to FC receptor on eosinophils so important against parasitic infections
eosinophils contain granules that realize cat Ionic proteins which are toxic to the parasites

18. IgE increases in IL 4 causes switching of Ig to IgE
Parasitic infections
Atopic patients
IL 4 causes switching of Ig to IgE
IL 5 causes eosinophilia

19. FceRI
degranulation
IgE
allergen
inflammation

20. Variants of Ig
Isotype all classes ,Subclasses & forms of Ig which present in normal individual
Allotype existence of allelic forms , single a.a. variation in the peptide chain of Ig ( genetic marker) IgG =GM, IgA=AM
Idiotype each Ig has its own antigenic determinant area against which an anti-idiotype Ab will be formed (Idiotype
antiidiotype network)

23. Characteristics of sp. Immune respond : 1-Discrimination (distinguish) between self & Foreign Ag Any Ag when reach the lymphoid tissue during pre-natal period suppress any further immunological response to that Ag in future ((self)) _colonel deletion theory _ During embryonic dev. All T & B lymphocytes that carry auto –reactive receptors for self Ag ( ( Auto-reactive cells) will be deleted by apoptosis self tolerance

24. 2- specificity Ab react specifically with Ag that causes its production ,sometimes can react with similar not identical = cross reaction β- haemolytic streptococci can lead to rheumatic heart dis. Because cross reaction between bacteria Ag & valve tissue in some individuals

25. 3-clonality We have more that 10 T & B lymphocytic clones (group) each clone with different Ag receptor, when the Ag enter the body lymphocytes bearing receptors that fit the epitope best are stimulated to divided (clonal selection theory) this response is called primary immune response 8

26. Clonal Selection of B Cells is Caused by Antigenic Stimulation

27. B lymphocyte development (2)

29. 4-Anamnest response :(memory) The primary I. R
4-Anamnest response :(memory) The primary I.R. (1st exposure) a-Lag phase (7days) Ab level is zero (time for finding appropriate Ag receptor) depend on nature ,routs, immune state b-Log phase Ab(mainly IgM) start to appear & increase logarythemly c-Plateau phase d-decline phase

30. Secondary I.R. (2nd exposure) there is memory cell so no lag phase ,Ab titer quickly shooting up times *There is genetic switching from IgM in the pri. I.R. to IgG in the 2nd I.R.

31. Primary I.R.
Secondary I.R.
* There is lag phase
*No lag phase
*IgM class
*Ab of IgG class
*Low affinity Ab
*Ab of high affinity
*Ab titer is low
*Ab titer is high
*The host exposure for the
1st time so no memory cell
*Host exposure for the 2nd
time there is memory cell
*Ab titer decline rapidly
*Ab titer decline slowly

32. Best example is the vaccination we give booster Doses(multiple doses) to shift the I.R. from primary to secondary I.R.

33. THANK YOU