Chapter 15 - The Immune System

Steps of B Lypmhocytes

1. activated by exposure to specific antigen

2. enters geminal center of secondary lymphoid organ

3. undergoes cloning

B lypmhocytes undergo multiple cell divisions and become ___ cells and ___ cells

memory; plasma

Plasma cells produce ____ antibodies/sec

2,000

Antibodies aka

immunoglobulins

IgG

production increased after immunization and secreted during secondary response

Main form of antibodies in circulation

IgG

IgA

main antibody type in exeternal secretions

IgE

responsible for allergic symptoms in immediate hypersensitivity reactions

IgM

function as antigen recpetors on lymphocyte surface prior to immunization and secreted during primary response

IgD

function as antigen receptors on lymphocyte surface prior to immunization, other functions unknown

Y-shapes protein structure

2 long, heavy H chains joined by 2 shorter light L chains

The bottom of Y-shapped protein is ________ across different antibodies, while the top is ________ and allows antigen specificity

constant; different

B lymphocytes have antibodies on the ___________

plasma membrane

When an antigen bonds to the antibody, the B cell is stimulated to

divide and produce more antibodies

Everyone has about ___ antibody molecules

10 ^ 20

Cytotoxic T Lypmhocytes have surface molecules called

CD8

Cytotoxic T Lymphocytes function

Destroy body cells that harbor foreign antigens

Cell-mediated destruction

T cells must touch target victim

How do T cells perform cell-mediated destruction?

1. secrete perforins to make large pore in cell

   1. Secrete granzymes to cause apoptosis through caspase

Helper T lymphocytes surface molecule

CD4

Helper T lymphocytes function

improve ability of B lymphocytes to bcome plasma cells that secrete specific antibodies and enhance ability of cytotoxic T cells to kill targets

Regulatory T lymphocytes function

inhibit response of B and killer T lymphocytes

People with genetic defiiencies in regulatory T lymphocyte production may develop

autoimmune disseases and allergies

Dendritic Cells

originate in marrow and migrate to most tissues

Dendritic cells function

Engulf and partially digest protein antigens, and display polypeptide fragments on surface for T cell to see

After activated by dendritic cells, T cells divide to form ____ and ___ cells

effector; memory T

Histocompatibility Antigens are found

on surface of all body cells except mature RBCs

How many genes code for histocompatibility antigens?

4

What chromosome is histocompatibiilty antigens coded on?

6

What requires an MHC match?

organ transplant

Class 1 MHC is made by

all cells except RBCs

Class 1 MHC normally present

self antigens

Class 1 MHC can also present

foreign antigens to activate killer T cells

Class 2 MHC are made by _____ and ____

antigen-presenting cells; B cells

Class 2 MHC molecules and foreign antigens are

presented togeteher to helper T lymphocytes

Killer T cells have what receptor for MHC-1?

CD8

Helper T cells have what receptor for MHC-2?

CD4

What is a T cell’s first response to a virus?

Virus is phagocytosed by macrophages or dendritic cells

After being phagocytosed, the viral foreign antigens are

moved to the surface of the presenter cell

After being moved to the surface, the foreign antigen forms

a complex with MHC-2 molecule

After forming a complex, macrophage secretes ___ to stimulate ___ and ___

IL-1; cell division; proliferation of T cells

What does macrophage secretion of iL-1 stimulate in helper T cells/

Mitosis

After stimulated by macrophages, helper T cells secrete ____ and ____

macrophage colony-stimulating factor ; gamma interferon

The stimulation of macrophage colony-stimulating facotr and gamma interforn promotes

macrophage activity

T helper cells also secrete

IL-2

IL-2 makes the macrophage produce ____ and activates ___

tumor necrosis factor; killer T cell activity

Activated helper T cells promote humoral response of B cells by binding to ____ and ____

foreign antigens; MHC-2

The binding of B cells to foreign antigens and MHC-2s stimulates _________, _____________, and ______ and ____

mitosis of B cells; conversion to plasma cells; production of antibodies ; memory B cells

The stimulation of the B cell binidng allows

class-switched antibody formation

What happens to activated T cells when infection is over?

they’re destroyed

Active T cells produce a

surface receptor called FAS and later a protein: FAS ligand `

Binding of FAS to FAS ligand induces

apoptosis

After infection, it takes _______ days before antibodies are detected in the blood

5-10

The 5-10 day delay of antibodies after infection is a _______ response

primary

Later expose to the same infection results in maximum antibody production in _______ hours

less than 2

The later exposure to the same infection is ______ response

secondary

development of the secondary response provides

active immunity

Active immunity is used

to make vaccines

Vaccines

stimulate primary response and active immunity without making the person sick

Thre ways to accomplish vaccines

1. killed virus

2. Live virus that can’t infect or replicate

3. Genetically engineered recombinant virus

Adjuvants

molecules that boost adaptive immune response when delivered with the vaccine antigens

Adjuvents increase

ability of antigen-presenting cells to activate B and T cell responses

Passive immunity

passing of anitibodies from one indivudal to another

Examples of passive immunity

1. mother to fetus

2. mother to child through breast milk

3. artificial immunization like snake anti-venom