Immunology

Variolation Lady Montagu

Edward Jenner Smallpox

Pathogens(such as bacteria,fungi, and viruses)

INNATE IMMUNITY(all animals)

• Rapid response

Recognition of traits sharedby broad ranges ofpathogens, using a smallset of receptors

•

Recognition of traits specific to particularpathogens, using a vastarray of receptors

•

• Slower response

Barrier defenses:SkinMucous membranesSecretions

Internal defenses:Phagocytic cellsNatural killer cellsAntimicrobial proteinsInflammatory response

Humoral response:Antibodies defend againstinfection in body fluids.

Cell-mediated response:Cytotoxic cells defendagainst infection in body cells.

ADAPTIVE IMMUNITY(vertebrates only)

Figure 43.2

Figure 43.3

Pathogen

PHAGOCYTICCELL

VacuoleLysosomecontainingenzymes

Thymus

Peyer’spatches(smallintestine)

Appendix(cecum)

AdenoidTonsils

Lymphaticvessels

Spleen

Lymphnodes

Lymphnode

Bloodcapillary

Interstitialfluid

Tissuecells

Lymphatic vessel

Lymphatic vessel

Masses ofdefensive cells

Figure 43.7

Figure 43.8-1

Pathogen Splinter

Mastcell

Macro-phage

Capillary

Redblood cells

Neutrophil

Signalingmolecules

Figure 43.8-2

Pathogen Splinter

Mastcell

Macro-phage

Capillary

Redblood cells

Neutrophil

Signalingmolecules

Movementof fluid

Figure 43.8-3

Pathogen Splinter

Mastcell

Macro-phage

Capillary

Redblood cells

Neutrophil

Signalingmolecules

Movementof fluid

Phagocytosis

Cytoplasm of B cell

Antigen-binding site

B cellantigenreceptor

B cell

Lightchain

Disulfidebridge

Antigen-binding site

Variable regions

Constant regions

Transmembraneregion

Heavy chains

Plasmamembrane

C C

C C

V

V

V

V

Figure 43.9

Figure 43.10a

AntibodyAntigenreceptor

B cell

Antigen Epitope

Pathogen

(a) B cell antigen receptors and antibodies

AntigenAntigenreceptor

Antibody

Plasma cellsMemory cells

B cells thatdiffer inantigenspecificity

Figure 43.14

Primary immune responseto antigen A producesantibodies to A.

Secondary immune response toantigen A produces antibodies to A;primary immune response to antigenB produces antibodies to B.

Exposureto antigen A

Exposure to antigens A and B

Time (days)

An

tib

od

y co

nce

ntr

atio

n(a

rbit

rary

un

its)

104

103

102

101

100

0 7 14 21 28 35 42 49 56

Antibodiesto A

Antibodiesto B

Figure 43.15

Humoral (antibody-mediated) immune response Cell-mediated immune response

Antigen (1st exposure)

Engulfed by

Antigen-presenting cell

Helper T cell

Memoryhelper T cells

Antigen (2nd exposure)

B cell

Plasma cells

Secretedantibodies

Defend against extracellularpathogens

Memory B cellsMemory

cytotoxic T cellsActive

cytotoxic T cells

Defend against intracellularpathogens and cancer

Cytotoxic T cell

Key

Stimulates

Gives rise to

Figure 43.20

Figure 43.22

IgE

Allergen

Histamine

Granule

Mast cell

Latency AIDS

Helper T cellconcentration

Years after untreated infection

Hel

per

T c

ell c

on

cen

trat

ion

(in

blo

od

(ce

lls/m

m3 )

Relative anti-HIV antibodyconcentration

Relative HIVconcentration

800

600

400

200

00 1 2 3 4 5 6 7 8 9 10

Figure 43.25