1
Immunology deals with understanding how the
body distinguishes between what is self and what
is nonself all the rest is technical
detail. (Benjamini et al.) The word immunity
is derived from a Latin word meaning exempt from
taxation
2
Historical perspectives on immunology
Ancient Greece if people recovered from
the plague they didnt catch it again
1718- Lady Montagu- variolation 1798- Edward
Jenner Louis Pasteur (1800s)- vaccine
design cholera (in chickens) anthrax (in sheep)
3
Von Behring and Kitasato, 1890 serum from
immunized animals could be transferred to other
animals and protect them (Kabat immunoglobulin,
1930s) Metchnikoff, 1883- phagocytes could
ingest microbes more phagocytes in immunized
animals Chase, Glick, 1950s importance of
lymphocytes
4
Lymphocytes are antigen-specific Why? Clonal
selection theory (Jerne, Talmadge, Burnet, 1950s)
is the prevailing paradigm
5
Clonal selection theory
p. 15
6
Clonal selection theory T and B cells with
different antigen specificities exist before they
encounter antigen Lymphocytes have
antigen-specific receptors on their
surfaces Once receptor combines with antigen,
the cells proliferate and differentiate into
clones Somehow, cells that recognize
self-antigens are prevented from developing
7
The immune reaction consists of two related
activities Recognition (of a specific foreign
substance pathogen or antigen) Response that
eliminates or neutralizes that substance memory-
subsequent exposure to that substance leads to
a faster, more intense response
8
What are the components of the immune
response? There are many! Innate
(non-specific immediate) Acquired (adaptive)-
specific, has memory
9
Components of innate immunity Prevent entry of
pathogen Prevent growth of pathogen Kill the
pathogen Eliminate pathogen and repair damage
10
p. 5
11
Ingestion by phagocytes
p. 40
12
Introduction to inflammation
p. 8
13
Vasodilation?erythema (redness) and
heat capillaries are more permeable Influx of
fluid (edema) Influx of phagocytes, which
release enzymes that kill cells. Pus is
produced Various chemicals are produced in the
inflammatory response- by the microbes, the
damaged cells, plasma proteins, and immune cells
14
Acute-phase proteins (activate complement) Histam
ine (promotes vasodilation) Kinins- become
activated and promote vaso- dilation Bradykinin-
stimulates pain receptors Increase in capillary
permeability allows blood-clotting proteins to
enter tissue What cells act in innate immunity?
15
Hematopoiesis In bone marrow
p. 25
16



Neutrophils Basophils Eosinophils Macrophages
Natural killer cells
17

• If innate immune cells are not
  antigen-specific,
• how do they become activated?
• Janeway, et al. proposes three mechanisms
• (summarized Science 296, 2002)
• Microbial nonself- cells detect conserved
• sequences that are present on microbes but
• not self (LPS, peptidoglycan)
• costimulatory signal by antigen-presenting
• cells (APCs)
• 2. Missing self- ligands that are normally
  present
• inhibit immune response. Example MHC
• class I

18
p. 333
19
Other structures signal different functions On
senescent or apoptotic cell- targeted
for phagocytosis Cell damage necrosis- repair?
Or does it induce an immune response (danger
model)
20
Acquired immunity
Unlike innate mechanisms, these
have Specificity Diversity Memory Self-nonself
recognition Principal types of cells are
lymphocytes and antigen-presenting cells
21
p. 11
22

• Immunological molecules
• Antigen receptors
• Antibodies
• Class I MHC molecules
• Class II MHC molecules
• Cytokines
• Membrane-bound receptors
• Plasma proteins
• Adhesion molecules
• Enzymes

23
MHC and antigen recognition
p. 13
24
Requirement for antigen-presenting cells
p. 14
25
Examples of antigen-presenting cells Macrophages
Dendritic cells B cells
26
Acquired immunity Clonal selection Proliferatio
n Enhanced secondary response
27
p. 17
28
Components of immune activation Antigen
recognition Requirement of T cell help for B
cell activation (Bretscher and
Cohn) Requirement of costimulatory signals for T
cells From antigen-presenting cells (APCs) APCs
themselves may not be constitutively active
29
Danger model (first proposed in early
1990s Matzinger and Fuchs) Activation signal
may be damaged tissue or cells How does immune
system continue to recognize self throughout
development? Why do different types of immune
responses occur in different tissues? Why are
fetuses tolerated by the pregnant woman?
30
p. 12
31
p. 16, humoral response
32
p. 16, cell-mediated
33

• Immunological molecules
• Antigen receptors
• Antibodies
• Class I MHC molecules
• Class II MHC molecules
• Cytokines
• Membrane-bound receptors
• Plasma proteins
• Adhesion molecules
• Enzymes

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p. 19
35
What happens when the immune system
malfunctions? Allergy and asthma Graft
rejection and graft-vs-host disease Autoimmune
disease Immune deficiency
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