The document discusses the adaptive immune response, which is an ever-developing system that continues to mature throughout life. In contrast to the innate immune response we are born with, the adaptive immune response initiates a specific attack against microbial invaders and remembers them so future attacks can be fought off quickly. It is characterized by specificity, memory, and the ability to recognize pathogens. The major components include antigens, antibodies, lymphocytes (B cells, T cells, NK cells), and the lymphatic system. B cells produce antibodies while T cells are involved in cell-mediated immunity. Together they provide protection against pathogens.

1. The Adaptive Immune Response.The Adaptive Immune Response.
BY: Ahmed Khalil IbrahimBY: Ahmed Khalil Ibrahim
University of GeorgiaUniversity of Georgia

2. Adaptive Immune ResponseAdaptive Immune Response
in contrast to the innate immune response which we arein contrast to the innate immune response which we are
basically born with, the adaptive immune response is anbasically born with, the adaptive immune response is an
ever developing systemever developing system
– it continues to mature throughout our lifeit continues to mature throughout our life
– in most cases as each new microbial invader isin most cases as each new microbial invader is
encountered, our adaptive immune response initiatesencountered, our adaptive immune response initiates
a specific attack against the invadera specific attack against the invader
– generally this invader is remembered and thatgenerally this invader is remembered and that
“memory”“memory” is readily available in the case of a secondis readily available in the case of a second
or subsequent attack from the same invaderor subsequent attack from the same invader

3. Adaptive Immune ResponseAdaptive Immune Response
the adaptive immune responsethe adaptive immune response
– is learned or acquiredis learned or acquired
– recognizes specific substances foreign to therecognizes specific substances foreign to the
bodybody
– is essential for lifeis essential for life

4. Adaptive Immune ResponseAdaptive Immune Response
other terms used for the adaptive immune responseother terms used for the adaptive immune response
includeinclude
– acquired immunityacquired immunity
– specific immunityspecific immunity
adaptive immune response is characterized byadaptive immune response is characterized by
– specificityspecificity
– memorymemory
– learned ability to recognize (acquired) pathogenslearned ability to recognize (acquired) pathogens
which allows the body to usually only suffer once fromwhich allows the body to usually only suffer once from
that particular pathogenthat particular pathogen

5. Components of the Adaptive ImmuneComponents of the Adaptive Immune
SystemSystem
antigensantigens
antibodiesantibodies
lymph systemlymph system
lymphocyteslymphocytes
– B cellsB cells
– T cellsT cells
– NK cell (Natural Killer)NK cell (Natural Killer)
Antigen
Antibody
B cell
T cell
NK cell

6. AntigensAntigens
the term antigen derives from the two wordsthe term antigen derives from the two words antiantibodybody
genegeneratorrator
most antigens are proteins or large polysaccharidesmost antigens are proteins or large polysaccharides
often a component of invading microbes, such as theoften a component of invading microbes, such as the
capsule, cell wall, flagella, toxincapsule, cell wall, flagella, toxin
– particular chemical that will activate the adaptiveparticular chemical that will activate the adaptive
immune responseimmune response

7. AntigensAntigens
two essential properties of antigens includetwo essential properties of antigens include
– immunogenicityimmunogenicity
the ability to stimulate immune systemthe ability to stimulate immune system
antigen-antibody
complex

8. AntigensAntigens
– specific reactivityspecific reactivity
the ability to react with effector moleculesthe ability to react with effector molecules
(antibody) to form an antigen-antibody complex(antibody) to form an antigen-antibody complex
Antigens in red with green borders

9. AntibodiesAntibodies
glycoproteins that are also referred to asglycoproteins that are also referred to as
immunoglobiulinsimmunoglobiulins
basic structure is a Y shaped molecule with 2 functionalbasic structure is a Y shaped molecule with 2 functional
partsparts
– Fab regionFab region
– Fc regionFc region
Fab region
Fc region

10. AntibodiesAntibodies
Fab regionFab region
– this is the part of the antibody that binds to thethis is the part of the antibody that binds to the
antigenantigen
Fc regionFc region
– the stem of the antibody that functions as a “red flag”the stem of the antibody that functions as a “red flag”

11. AntibodiesAntibodies
there are 5 classes of immunoglobulinsthere are 5 classes of immunoglobulins
– each class plays a different role in the immuneeach class plays a different role in the immune
responseresponse
IgGIgG
IgMIgM
IgAIgA
IgDIgD
IgEIgE

12. Lymphoid SystemLymphoid System
in regards to the immunein regards to the immune
system the lymphaticsystem the lymphatic
system consists of tissuessystem consists of tissues
and organs that areand organs that are
designed and located todesigned and located to
convey the B and T cellsconvey the B and T cells
into contact with all antigensinto contact with all antigens
that enter the bodythat enter the body

13. Lymphoid SystemLymphoid System
– primary lymph organsprimary lymph organs
bone marrow: the location of stem cellsbone marrow: the location of stem cells
that will eventually become B and Tthat will eventually become B and T
cells, B cells mature in the bonecells, B cells mature in the bone
marrowmarrow
thymus: maturation of the T cellsthymus: maturation of the T cells
Healthy bone marrow Bone marrow with leukemia
Lymph node

14. LymphocytesLymphocytes
critical part of immune system responsible forcritical part of immune system responsible for
– detection of foreign antigensdetection of foreign antigens
– activate immune systemactivate immune system
B lymphocytesB lymphocytes
T lymphocytesT lymphocytes
natural killer cells (NK cells)natural killer cells (NK cells)

15. B lymphocytes: B cellsB lymphocytes: B cells
antibody producing cellsantibody producing cells
that respond to anthat respond to an
antigen stimulationantigen stimulation
develop from stem cellsdevelop from stem cells
located in the red bonelocated in the red bone
marrow of adults and themarrow of adults and the
liver of a fetusliver of a fetus
B Cells dividing

16. B lymphocytes: B cellsB lymphocytes: B cells
following maturation, theyfollowing maturation, they
migrate to the lymphaticmigrate to the lymphatic
tissuetissue
B cell in lymph node

17. T lymphocytes: T cellsT lymphocytes: T cells
key cellular component ofkey cellular component of
immunityimmunity
develop from stem cellsdevelop from stem cells
found in the bone marrowfound in the bone marrow
precursors to T cellsprecursors to T cells
migrate to the thymus,migrate to the thymus,
where they reach maturitywhere they reach maturity
human T cells

18. T lymphocytes: T cellsT lymphocytes: T cells
following maturity, T cells migratefollowing maturity, T cells migrate
to various lymph organs whereto various lymph organs where
they await contact with antigensthey await contact with antigens
basis for cell-mediated immunitybasis for cell-mediated immunity
T cells (on left – orange,
on right – gray) killing
cancer cells (on left- mauve.
on right – red)

19. Natural KillerNatural Killer
CellsCells
these cells are not immunologically specificthese cells are not immunologically specific
– they do not need to be stimulated by an antigenthey do not need to be stimulated by an antigen
capable of destroying other cells, particularly viruses-capable of destroying other cells, particularly viruses-
infected cells and tumor cellsinfected cells and tumor cells
also can attack large parasitesalso can attack large parasites

20. Clonal Selection of LymphocytesClonal Selection of Lymphocytes
terms used to define various stages of clonalterms used to define various stages of clonal
selection includeselection include
– immatureimmature
– naïvenaïve
– activatedactivated
– effectoreffector
– memorymemory

21. Antibody-Mediated ImmunityAntibody-Mediated Immunity
humoral or antibody-mediated immunity involveshumoral or antibody-mediated immunity involves
antibodies that are produced by B cellsantibodies that are produced by B cells
– the term humoral is derived from the word “humors”,the term humoral is derived from the word “humors”,
which is Latin for fluidwhich is Latin for fluid
in response to foreign antigens, the B cell is activated toin response to foreign antigens, the B cell is activated to
produce a clone of plasma cells and memory cellsproduce a clone of plasma cells and memory cells
– plasma cells secrete antibodiesplasma cells secrete antibodies
– memory cells recognize pathogens from previousmemory cells recognize pathogens from previous
encountersencounters
B memory cells are long lived and are ready toB memory cells are long lived and are ready to
mount an attack the next time that specific antigenmount an attack the next time that specific antigen
presents itselfpresents itself

22. Primary & Secondary ResponsePrimary & Secondary Response
The body can make low levels of soluble
antibody about one week after exposure to
antigen. However, a second exposure to
antigen produces a much faster response,
and several orders of magnitude higher
levels of antibody. The ability of antibody to
bind antigen also increases in the secondary
response. The memory of antigen and
stimulated response is the basis for
vaccination

23. Antibody-Mediated ImmunityAntibody-Mediated Immunity
the antigen-antibodythe antigen-antibody
complexes that are formed ascomplexes that are formed as
a result of antibodies producea result of antibodies produce
by B plasma cells attractby B plasma cells attract
phagocytesphagocytes
Bacteria in green

24. Antibody-Mediated ImmunityAntibody-Mediated Immunity
phagocytosis destroys the pathogen and control ofphagocytosis destroys the pathogen and control of
the disease is accomplishedthe disease is accomplished
Bacteria