MIC 205 Exam 4: Chapter 16. Adaptive Immunity

Specific Defenses

Third line of Defense: lymphocytes, antibodies ( specific immune response)

AB is a another name for what?

Antibody

Characteristics of Specific Immunity

• The body’s ability to recognize and defend itself against distinct invaders and their products

• “Smart” system - memory function allow for rapid response to subsequent encoutners with familiar pathogens

• Acquired over time as the body “teachs” its immune cells about differences between foreighn and self

What is an Antigen?

Any molecule or molecular fragment that triggers a specific immune response

What are included in antigens?

Components of bacterial cell walls

capsules

proteins of viruses, fungi, and protozoa

What is an Epitope?

A defined region or frageent of a molecule that has antigentic properties; note that a simple large molecule ( e.g. protein) may possess multiple epitopes

Food and dust also can contain antigentic particles

They are antigens, but they are a specific area of the protein ( which is also an antigen)

Induce a separate response ( subareas of the antigen)

Induce a strong response

Three different ways Antigens enter the body

1.) Through breaks in the skin and mucous membranes ( portal of entry / break in skin)

2.) Direct injection, as with a bite or needle ( vaccine)

3.) Through organ transplants and skin grafts

Do antigens have to be a certain molecule weight?

Yes, it has to be a big enough, or the immune system will ignore it

Example of an antigen the immune system ignores

Penicillin and other drugs due to their size

Other examples of Antigens

Lactose, Foods, Air molecules

Are proteins and molecules considered antigens?

Yes

Lymphatic System

A nework of organs, fluid-retun vessles, and clean-up cells that screen the tissues of the body for foreign antigens

Components of Lympathic System

Lymphoid Cells

Lymphatic Vessels

Lymph Nodes

Spleen, tonsils, etc

Lymph

Liquid similar in composition to blood plasma that arises from fluid leaked from blood vessels into surrounding tissues

Lymph is a ___ fluid?

immune

Lymph arises from where?

fluid leaked from blood vessels into surrounding tissues

Lymphoid Cells include:

Lymphocytes ( T-cells and B Cells)/ smallest of the WBCS

Where do lymphoid cells develop?

Stem cells in the red bone marrow

Lymphatic Vessels

One-ways system that collects lymph from tissues to the lymph nodes and returns it to the circulatory system

Lymph Nodes

House leukocytes that recognize and attack foreign antigens in lymph

Where are lymph nodes concentrated in?

Neck, groin, armpit,and abdominal regions

Third line of Defense mainly occurs where?

Lymphoid Cells, Lymphatic Vessels, and Lymph nodes

Any damaged/ cells bacteria are filtered into where?

The Lymphatic System

Spleen

• similar in structure and function to the lymph nodes

• Filters bacteria, viruses, toxins, and other foreign matter from the blood

Tonsils and mucosa-associated lymphoid tissues (MALT)

physically trap foreign particles and microbes

Mucosal tissues include ( MALT)?

appendix

lymphoid tissue of the respiraotry tract

Peyer’s patches of the wall of the small intestine

Lymphocytes (Overview)

• aries and mature in red bone marrow ( B cells) or thymus ( T-Cells)

• Clonal Deletion

• Found in the spleenand lymph nodes

• Small percentage of them circulate in the blood

• Activated ( Clonal Selection) by a single matching antigen will result in cell division

• Produce memory cells for later response

B-lymphocytes ( B cells ) arise from where?

Red bone Marrow

T lymphocytes ( T cells ) arise from where?

Thymus

Where do majority of lymphocytes stay in?

Spleen, but a small percentage of them are in the blood

Clonal Deletion

• Occurs with B and T Cells

• Critcial that immune response directed against antigens derived from your “self” molecules ( autoantigens)

• Body “edits” lymphocytes to eliminate all self-reactive cells

What cells in the bone marrow give rise to B cells?

Stem cells

B cells that respond to self Ag are

normally inactivated by Clonal Deletion ( self vs non-self)

Assortment of B Cells ( heterogenity)

• During maturation, randomization of variable region receptors

• Each cells has two matching receptors

• Ag binds specifically to the antibody of the B cells ( specificity)

Activated B Cells Differentiate

• Plasma cells synthesize/ secretes antibodies

• Memory cells wait for restimulation by the same Ag later ( memory)

What is are antibodies?

Soluble proteins composed of polypeptides that are held together by covalent bonds

Where do antibodies circulate?

Blood and lymph where they find their counterpart antigen

What are antibodies secreted from?

Plasma cells which are B cells that are actively fighting antigens

Are antibodies considered part of the humoral immune response?

Yes, since bodily fluids like lymph and blood once were called humor

Structure of Antibodies

• Four polypeptides

• Covalent Bonds

• Heavy ( large) chains and light ( small) chains

• Two antigen-bind sites per antibody molecules

• FC region

What is another name for the FC region?

The Constant Region

• FC/ Constant region is more common among Antibodis

The Heavy and Light chains are bonded by what bond

Disulfate bonding, a type of Covalent bond

The Antibody class involved in the immune response depends on these factors:

• Type of foreign antigen

• Portal of entry

• Antibody function

What are the five different classes of Antibodies?

• IgA

• IgD

• IgE

• IgG

• IgM

IgM

the primary antibody

shape: pentameric

First class of antibody in the humoral system

IgG

most prominnt in the immune system

shape: monomeric (Y-shaped)

IgA

Found in mucous membranes

Associated with breast milk, transferred from mom to baby, and they are protectory for the baby

shape: Dimeric

What is the class of antibody that is closely related with breast-milk/ breast feeding

IgA

IgG

Shape: Monomeric

Function: Allergic Reactions and other immune responses

IgD

Function: Not Known

Very first antibody that was produced by mammalians

Shape: Monomeric

Antibody Function

• Form strong, noncovalent interactions with antigen

  • Binding occurs because antibody’s antigen-binding sites are complementary to antigeneic determinants ( epitopes)

  • Interactions involve hydrogen bonds and other attractions

What type of bonds are formed between an antigen and an antibody

Noncovalent bonds

What are the several roles of the Antibodies?

• Activation of Complement System

• Stimulation of inflammation

• Agglutination

• Neutralization

• Opsonization ( phagocyte activation)

Activaton of Complement System and Stimulation of Inflammation ( Antibody Functions)

Chemicals signals tied back to 2nd line of defense for activation of complement system and stimulation of inflammation

Agglutination ( Antibody Function)

Crosslinking of antibodies to microbes —> removing of structures —> entice phagocyte to engulf the microbe —> Agglutination

Neutralization

Antibodies bind to glycoprotein spikes —> neutralizes the potential microbes by binding the glycoprotein spikes on the virus —> needs ligand to bind to receptor ( neutralizing)

Can toxins be neutralized by the antibody’s binding

yes, toxins can be neutralized by the antibody’s binding thus neutralizing the toxin

Opsonization

Performed by the complement system ( Complement protein binds to microbe —> signals immune system —> Phagocyte adheres to microbe for removal)

Process of Opsonization

Antibodies attach antibody to microbe —> Phagocyte comes in and attaches to antibody —> Phagocytosis can occur

Antigen receptors can recognize antigens which can cause it to?

Proliferate

Humoral Immune Response

Antibody-mediated responses mounted against exogenous pathogens

Components of the Humoral Immune Response

• B cell activation

• Clonal selections

• Formation of plasma B Cells

• Formation of memory B cells and immunological memory

When concerning humoral immune response, antibody-mediated responsed are mounted agains exogenous pathogens or endogenous pathogens?

Exogenous Pathogens

Plasma Cells only secrete ___?

Antibodies

Where are plasma cells located?

In the endoplasmic reticulum

What class of antibodies are secreted first?

IgM

When does the class switch of Antibodies occur?

It occurs when a mature B cells when activated by an antigen, changes the type of antibody it produces from IgM to antother antibody class ( typically IgG)

What happens to memory cells?

They are not used to remove the antigen, so they stay dormant

However, they are used again during a second response to the same antigen ( can take months or years to occur)

Plasma Cells

Make up the majority of cells produced during B cell proliferation

Plasma cells secrete only antibody molecules that are ___

complementary to the specific antigenic determinant

Are plasma cells short lived?

Yes, plasma cells are short lived they die within a few days of activation, through their antibodies and progency can persist

Do Memory B cells secrete antibodies?

They do not secret antibodies

Memory B cells display what on their membranes?

They display antibodies that are complimentary to the sepcific antigentic determinant that triggered their production

Are Memory B Cells long-lived?

Yes, they are long-lived cells that divide only a few times and then persist in the lymphoid tissue

Can memory B cells initiate antibody production if the same antigen is encountered again?

Yes, they are able to initiate antibody production

Truth about antigen binding to B Cells

• It is rare that free Ag bind directly with B cells

• Usually, Ag presented by antoher cell will produce a signal ( cytokines) to activate

Antigen Presenting Cell ( APC)

Display Ag on their surface to T-helper cell

T helper cell ( Th1 or Th2 cell)

Will direct the response via chemical signals such as interleukins ( IL)

Why do antigens present Ag on their surface to T-helper cells

To stimulate a more cell-mediated response with the assistance of T-Helper cells

T-helper cells with direct the response via chemical signals such as interleukins (IL)

Lysing

Needing more of the humoral response to kill everything after lysing cells

How many days does it take to seecrete IgM antibodies

5 days

IgM switches to IgG at appropximately at this day?

Roughly Day 6 or 7

What day is the peak amount of IgG during primary exposure?

Day 14

How many days does it take for the immune response to be fully activated?

10-14 days

What happens during a second exposure to a disease?

1.) Memory Cells become activated

2.) Memory cells make plasma cells

3.) Plasma cells make more antibdoies and memory cells

IgM 1st, IgG 2nd,

IgM produced at day 6

Max production of IgG at day 6

What is the difference between the second exposure and the first exposure to an antigen?

The immune response for the second exposure is more robust and happens faster

Are T-cells cell mediated immunity or humoral imuunity?

T-cells are cell mediated immunity

T Helper Cells (CD4)

Recognize MHC (safeguard signal)/ Ag complex from APC

Direct the specific immune response

T-cytotoxic Cells (CD8)

Triggers Apoptosis

Activated by Interleukin 2 produced by T helper cells

Attacks any cells carrying incorrect Ag/ MHC complex

Defense against cancer, virus-infected cells, tissue and organ transplant

T-cells serve protection against

Intercellular organisms, viruses, and cancer

What happens if you take away T-helper cells?

You are taking away the 3rd line of defense

What do T-helper cells recognize?

MHC

What T Cytotoxic Cells (CD8) do?

They tell cells to commite apoptosis

Where are Type T Lymphocytes ( T Cells) produced?

In the red bone marrow and MATURE in the thymus

Why must T-cells recognize MHC

This allows the immune system to remove foreign cells

examples: blood incompatibility, organ transplants

Where do T-cells circulate

Lymph, blood, and migrate to the lymph nodes, spleen, and Peyer’s patches

What percentage of B-cells are stored in the spleen?

10%

Are T-Cels part of the cell-mediated immune response?

Yes, because they act directly against various pathofens

• They respond to intracellular pathogens and abnormal body cells

What are the most common intracellular pathogens

Viruses and intracellular bacteria