1. Adaptive (specific ) Immunity
Adaptive immunity is a system of defenses that specifically targets billions of different antigens an individual may encounter during its lifetime
Antigen
PAMP or other molecule the body recognizes as nonself that triggers an active immune response

2. Overview of Adaptive Immunity
Vertebrate adaptive immunity adapts to different antigens it encounters during its lifetime
Lymphocytes and phagocytes interact to effect four defining characteristics: Self/nonself recognition, specificity, diversity, and memory

3. Key concepts about immune cells
1. The principle cells of the immune system:
Antigen-presenting cells  Lymphocytes => Effector cells
2. All immune cells are derived from “Hematopoietic stem cells”
in Bone Marrow (BM) (& Fetal liver during fetus).
3. Immune cells are divided into two major lineages:
=> Lymphoid & Myeloid
=> Multiple cell types => express distinct “Surface molecules (markers)” => classification
4. Development and differentiation of different cell types
depend on cell interactions and cytokines.

4. Self/Nonself Recognition
Self versus nonself recognition
Each kind of cell or virus has a unique identity
MHC markers
Plasma membrane self-recognition proteins
T cell receptors (TCRs)
Antigen receptors that recognize MHC markers as self, antigens as nonself

5. Specificity and Diversity
Defenses are tailored to target specific antigens
Diversity
There are potentially billions of different antigen receptors on T and B cells

6. Memory
Memory
The capacity of the adaptive immune system to remember an antigen
If the same antigen appears again, B and T cells make a faster, stronger response

7. First Step – The Antigen Alert
Once a B or T cell recognizes and binds to a specific antigen, it begins to divide by mitosis
All descendent cells recognize the same antigen
T cells do not recognize an antigen unless it is presented by an antigen-presenting cell
Macrophages, B cells, and dendritic cells digest particles and display antigen-MHC complexes

8. Cell Types Effector cells Memory cells
Differentiated lymphocytes (B and T cells) that act at once to fight infection
Memory cells
Long-lived B and T cells reserved for future encounters with the same antigen

9. Antigen Processing

10. Two Arms of Adaptive Immunity
Cell-mediated immune response
Cytotoxic T cells and NK cells detect and destroy infected or altered body cells
Antibody-mediated immune response
B cells produce antibodies that bind to specific antigen particles in blood or interstitial fluid

11. Interactions Between Antibody-Mediated and Cell-Mediated Responses

12. Interactions Between Antibody-Mediated and Cell-Mediated Responses

13. T Cell Receptor =TCR

14. Cytokines

15. Cytokines

16. Cytokines receptors