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Specific Immunity

Chapter 15

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SPECIFICITY MEMORY

Fig 14.25

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2 branches of the adaptive immune

system1. ______________immune system- takes

place in body fluids; B cells secrete

antibodies that attack antigens

2. ______________immune system takes

place between the T cells and antigens

(infected, cancerous or other types ofcells.

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____________ (foreign invader) a substance thatis recognized as foreign or nonself by theimmune system. May be a whole microorganismor a portion of it.

___________________- (defensive weapon) a Y-shaped protein which is produced & secreted by Bcells in response to a specific antigen. Antibodiesbind to & contribute to the destruction of antigens.

Antigen

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Structural & chemical

characteristics of antibodies1. Also called _____________________

2. highly specific proteins that interact with only ____

antigenic determinant (_____________) on an antigen

3. serve as __________________receptors for B cells

4. each Ab has ___identical binding sites for___________

5. a typical Ab monomer has ___protein chainsa. 2 identical Light (L) chains

b. 2 identical Heavy (H) chains

6. each H & L chains has a variable region & a constant

region

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Fig 15.5

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variable region - located at the end of the Y arms

account for ability to bind specific Agthousands of possibilities

constant region - located at the stem & lower parts of

the Y arms___major types of constant H regions ( G,M,A,D,E)

___major types of constant L regions ( kappa, lambda)

stem of the Y called Fc region

Fc can bind to host cells

Fc of G & M classes of Ab can activate complement

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Characteristics of each of the 5

classes of antibodies1. IgG

cross placenta & confer passive immunity to fetus

trigger complement system

2. IgM

pentamer 5 monomers & a J chain

trigger complement system

first antibody to appear after initial exposure to Ag

Table 15.2

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3. IgA

high amounts are in mucous, saliva, & breast milk

secretory IgA dimmer- 2 monomers & a J chain & asecretory component

main function is to prevent attachment of pathogens to

mucous membranes

4. IgD

acts as antigen receptor on B cells

No known function in serum

5.IgE bound to mast cells & basophils by Fc end, serve as Ag

receptors & binding causes release of histamine &chemicals allergies

useful against parasitic worms

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Fig 15.14

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Antigen

Epitopes orAntigenic determinants

4

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Whathappens afterantibodies

bind toantigen?1. ____________________ - block virus

attachmentto cell, block toxin's active site

2. ________________________(opsonization, inflammation, lysis)

3. ____________________ - clumps Ag

together-helps phagocytosis

4. __________________ -helps phagocytosis

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Fig 15.16

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Primary vs Secondary immune

responses

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Antibodysecretors

Memorycells

Absecretors

Memory

cells

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Primary immune response

Slower

Weak response

Few specific B & T cells

Few antibodies made

Secondary immune response

Faster

Strong response

More specific B & T cells

Lots of IgG made quickly

Basis for vaccines &booster shots

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Cell mediated immunityT cells

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How does the Cellular Immune System

distinguish between self and nonself?

All body cells have Major HistocompatabilityComplex (MHC) class I proteins on their surfaces

that mark the cells as self Immune system tries to destroy anything that does

not have class I proteins because they are nonself,or antigens

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T cell

Foreignantigen

MHC

T cell receptor recognizes

self MHC plus foreign antigen

Body cell

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T cells Derived from bone marrow and mature in thethymus

Make up _______% of circulating lymphocytes

Each has a T cell antigen receptor which recognizes

a peptide bound to a self MHC molecule

Do not recognize soluble, ______________antigen

Antigen must be displayed on surface of an antigen

presenting cell like a B cell or macrophage

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T cell antigen receptor

Fig 15.7

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3 Types of T cells

Helper T4 Co c o of e sys ec e o e cells of e sys e

Cy o o c T8 es oy e cells o co c

Re l o y T off e espo ses

Self ole ce

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Cytokines

Chemical messengers of the immune cells

Signal cells to move into area, become

active, replicate, etc.

used to communicate among WBCs

Interleukin 1 (IL-1)

Interferon (IFN)

Tumor Necrosis Factor (TNF)

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Humoral

immunity

Cell-mediated

immunity

Cell types B cells, plasma

cells

T cells (3 types)

Secretions Antibodies Cytokines to

communicateAntigens Freely circulating

bacteria, viruses,

etc.

Intracellular

parasites,

transplants, cancer

RequiresT cell

stimulation

Yes Yes