Talk given at Columbia College, Vancouver BC

1. Columbia College mini-lecture
Philippe Henry PhD, Thursday April 9th 2015
A broad overview of the immune system

2. Based on chapters 1 & 2 of Kuby, Immunology (6th edition) 2007
Outline:
- background on
importance of the
immune system
- innate and
adaptive
response
- cells of the
immune system
(time permitting)

4. The principal function of the immune system is to
protect the host against pathogenic microbes.

5. Overview of the immune system
Immune system
Innate
(nonspecific)
1st line of defense
Cellular
components
Humoral
components
Adaptive
(specific)
2nd line of defense
Cellular
components
Humoral
components

6. Innate immunity is present in all
multicellular plants and animals
but only vertebrates have
adaptive immunity.
Innate Immunity is
ubiquitous
6

7. Innate Immunity: cellular and molecular mechanisms predeployed
before an infection and poised to prevent or eliminate the invader
-skin, mucous membranes, stomach acidity, phagocytes
-1st line of defense
Adaptive Immunity: develops in response to infection and adapts to
recognize, eliminate and remember the invading pathogen
- contingent on the innate response: signal
- antigen presenting cells, lymphocytes, antibodies
-2nd line of defense

8. Innate Immune Response

9. • Recognition
– Self/Non-self
Discrimination
• Response
– Effector: neutralizes/
eliminates invader
– Memory: prevents
second infection;
“educates” the
immune system for
later attacks
Adaptive Immune
Response

10. • Primary lymphoid organs:
thymus and bone marrow is
where lymphocytes mature
• Secondary lymphoid organs:
lymph nodes, spleen, mucosa-
associated lymphoid tissues
and gut-associated lymphoid
tissues provide sites for
mature lymphocytes
(antigenically committed) to
interact with antigen
• Connected via lymphatic
vessels and blood

11. Cells of the immune system
Immune system
Myeloid cells
Granulocytic
Neutrophils
Basophils
Monocytic
Macrophages
Kupffer cells
Dendritic cells
Lymphoid cells
T cells
Helper cells
Suppressor cells
Cytotoxic cells
B cells
Plasma cells
NK cells
-lymphocytes ( T and B) and
antigen-presenting cells
-connect innate and adaptive
responses

12. Key Cells & Overview of their Function
Major
Phagocyte
Minor
Phagocyte

13. Cells of the immune system: innate
• Phagocytes
– Monocytes/macrophages
– Dendritic cells
• Basophils and mast cells
• Platelets
• NK cells

14. Phagocytes – 1) macrophages
• Ingest and digest
whole microbes and
present Ag to helper
T cells
• CD14

15. Phagocytes – 2) neutrophils
- first to arrive at site of injury playing a key role in the front-line defense against
invading pathogens
- express & release cytokines: amplify inflammatory reactions by other cells
- release soluble anti-microbials

16. • Are complicated
• Excellent phagocytes
• Antigen-presenting cells
Phagocytes – 3) dendritic cells

17. Basophils and Mast cells
• Allergies
• Mast cells are anti-
parasites
• Mast cells are minor
phagocytes

18. Natural killer (NK) cells
• large granular
lymphocytes
• Kill virus-infected or
transformed cells (no
Ag recognition
receptors)
• Cytotoxicity
mechanisms not well
understood

19. Cells of the immune system: APC
• Cells that link the innate and adaptive arms
– Antigen presenting cells (APCs)
• Heterogenous population with role in innate immunity
and activation of Th cells
– Examples
• Phagocytes like macrophages and dendritic cells
• B cells

20. Cells of the immune system: adaptive
• Lymphocytes
– B cells
• Plasma cells (Ab producing)
– T cells
• Cytotoxic (CTL)
• Helper (Th)
– Th1
– Th2
– Th17
– T-reg

21. - B lymphocytes mature in bone
marrow
- antigen binding receptor is a
membrane bound Ab
- antigen presenting cell
- binding causes cell division
and differentiation into
memory B cells which
produce secreted Ab

22. - T lymphocytes arise in bone marrow but
migrate to the thymus gland to mature
-T-cell receptor (TCR): Th (CD4), Tc (CD8), T
reg (CD4 + FoxP3)
-T cells don’t bind antigen directly like B cells
but rather ONLY when the Ag is presented
with MHC on APC

24. Thank you