1. IMMUNE SYSTEM

2. The immune system
•
What is the main function of the immune
system?
•
What is a pathogen?

3. The defense mechanisms
•
1st line vs 2nd line vs 3rd line of defenses

4. Give the function of these cells
•
Monocytes APC coelomocytes
•
Macrophages Basophil
•
Neutrophil Eosinophil
•
Mast cell NK cell
•
Cytokine cytotoxic T cell
•
effector cell helper T cell
•
memory cell suppressor T cell

5. The chemicals and others
•
Perforin Chemokine
•
Interferon antibody
•
Antigen antigen receptor
•
Cd4 Cd8
•
Histamine Interleukin
•
Lysozyme prostaglandins
•
Pyrogens Rh factor

6. The innate immunity
•
What happens to you if you caught a virus or
an infection?

7. Inflammation and Sepsis
•
Release of histamines (pathogen/self cell)
•
Dilation and inc permeability of BV
(prostaglandin)
•
Increased blood flow
•
Inflammation (redness and swelling)

8. Phagocytic cells
•
Neutrophils are first to arrive
•
Macrophages will also arrive

9. Chemokines
•
Messenger chemical
•
Attracts phagocytic cells
•
Activation of lysozyme action

10. Severe infection
•
Fever is an immune response to severe
infection
–
Can be caused by the pathogens
–
May be due to pyrogens released by some
leukocytes
–
Can facilitate phagocytosis
Septic shock- high fever, hypotension

11. Antimicrobial proteins
•
Proteins that attack microbes or stall
reproduction of microbes
•
Lysozyme is an example
•
Also, presence of the complement system
–
Made up of 20 serum proteins
–
Action: lysis or attraction of phagocytic cells
–
Is also part of specific immune response

12. Interferons
–
Secreted by virus-infected cells
–
Neighboring cells are stimulated to produce
chemicals that can inhibit viral infection
–
Not virus-specific
–
A specific type of interferon activates phagocytes

13. Self vs Non-self
•
Have you asked yourselves the question who
am I?

14. Self vs Non-self
•
Lymphocytes react on special surface
glycoproteins encoded by genes called Major
Histocompatibilty Complex (MHC)
•
In Humans, Human Leukocyte Antigens (HLA)
•
Class I MHC- Almost all nucleated cells
•
Class II MHC- macrophages, B cells, activated T
cells, cell in the interior of the thymus
Varies from one person to another

15. Specific immunity: the third line of
defense
•
Lymphocytes- cells responsible for the specific
immune response
•
There are two types: B cells and T cells (NK cells
another type)
•
Antigen- molecules that elicit specific response
from lymphocyte
–
E.g. Molecules from bacteria, fungi, virus, parasitic
worms
•
Antigens activate B cell in producing antibodies

17. Recognition of antigens by B cells
and T cells
•
Specificity is possible because of membrane-
bound antigen receptor
•
B cell antigen receptor- transmembrane version
of antibodies
–
Also called membrane antibodies
•
T cell antigen receptor- called T cell receptor
–
Structurally related to membrane antibodies
–
T cell receptor never released in secreted form

18. Clonal selection

19. Clonal selection
•
Antigen binds to a specific antigen receptor (B
cell)
•
B cell produces its clone
•
Some B cells become plasma cells (short-lived)
that can secrete antibodies to the specific
antigen
–
Plasma cells- also called effector cells
•
Some B cells become memory cells (long-lived)
for re-exposure to the antigen

20. Immunological memory
•
Primary immune response- selective
proliferation and differentiation of lymphocytes
upon first exposure
–
10-17 days to develop maximum effector cells
–
Selected B cells and T cells produce their respective
effector cells

21. Immunological memory
•
Secondary immune response- re-exposure to
the same antigen
–
response is faster, greater magnitude, more
prolonged
–
Also, more antibodies are produced
–
Antibodies have greater affinity to the antigens
–
Secondary response is called immunological
memory

22. Graph showing immunological
memory

23. Lymphocyte development
•
All blood cells develop from pluripotent cells
•
Lymphocytes also develop from pluripotent
cells
•
T cells- mature in the thymus
•
B cells- mature in the bone marrow

24. Immune tolerance for self
•
Maturing lymphocytes’ antigen receptors are
rendered non-functional
•
If antigen receptors cannot be switched off,
lymphocytes undergo apoptosis

25. The other cells....
•
Cytotoxic T cells- kill cells through lysis
•
Helper T cells- bind to antigen cell and secretes
cytokine
•
Antigen-presenting cells (APCs)- engulf bacteria
(virus) and present fragment of these
pathogens to other lymphocytes

26. Humoral response and cell-mediated
response
•
Humoral immunity- involves B cell activation,
production of antibodies in blood plasma and
lymph called humor
•
Cell-mediated immunity- action of T cells

27. Overview of humoral response
•
Macrophage engulfs the pathogen
•
Class II MHC binds to fragment of pathogen
•
MHC-antigen complex is presented by the
phagocytic cell
•
A helper T cell with specific receptor for the
antigen makes contact with the macrophage
and releases cytokines

28. Overview of humoral response
•
Activated T cell presents the antigen to a B cell
•
Cytokines activates the B cell
•
Activated B cells differentiate into plasma and
memory cells
•
Plasma cells will produce the specific antibodies

29. Cell-mediated immune response
•
Occurs when antigen displayed by APC activates
Cytotoxic T cell
•
Cytotoxic cell can differentiate to Memory T
cells or active cytotoxic T cells
•
Active against cancer cells and pathogens
•
Kills these cell through lysis

30. Antibodies
•
Do not destroy antigens directly
•
Rather, neutralizes it or present it as a target for
opsonization, agglutination, precipitation, or
complement fixation, neutralization

31. Antibodies
•
Opsonization- coating of antigens by antibodies
to facilitate phagocytos
•
Neutralization- binds to the antigen and
inactivates it
•
Agglutination- clumping of bacteria or virus to
effectively neutralize or opsonize it
•
Complement fixation or precipitation- immune
adherence occurs
–
Microbes coated with antibodies and complement

32. The ABO blood type
•
A and B are the antigens
•
Type A has antigen A and antibody B
•
Type B has antigen B and antibody A
•
Type AB has both antigen but no antibody
•
Type O has no antigen but has both antibody

IgM not IgG

33. Rh Factor

IgG can cross the placenta

++ = +

+- = +

- - = -

34. Passive vs Active

Passive

short-lived

Active

Natural vs artificial

35. Immunodeficiency vs Autoimmune
disease