Exam #4

What is the purpose of vaccination?

Exposing people to harmless versions of pathogens.

Result in protection.

Mimics what happen during adaptive immune response without resulting in disease.

Where do immature B and T cells originate?

Red bone marrow

Where do B and T cells mature?

B cells: bone marrow T cells: thymus

What are the 2 branches of the adaptive immune system?

Humoral immunity: B cells + produce antibodies

Cell-mediated immunity: T cells.

What is an antigen?

Body produces specific antibodies

What is an anitbody?

Protein produced by B cells responding to antigen that combines specifically with that antigen.

What is an epitope?

Specific region of antigen where an antibody binds.

What does valence refer to?

Number of antigen-binding sites on an antibody. (most have two binding sites: bivalent)

Describe the structure of a monomeric antibody.

Monomer: single bivalent antibody.

4 protein chains: 2 identical light chains, 2 identical heavy chains.

Chains joined by disulfide bonds.

Y

What is the function of an antibody's variable region?

Antigen binding site to epitope.

Function of constant region?

Where antibody is at.

5 classes of immunoglobulins, their structures, and functions (pay attention to the information on the slides in bold).

IgG, IgA, IgM, IgE, IgD.

IgG: Monomer. Protect against ALL infections. Activate complement.

IgA: Dimer. Mucous membranes and body secretions.

IgM: Pentamer. Serum and lymph. First antibody produced in response to infection, Agglutinate microbes efficiently, Activate complement.

IgE: Monomer. Defend against allergens. Lysis of parasitic worms, some allergic reactions.

IgD: Monomer. On surface of B cells. ACTIVATE B-cells.

What cells produce antibodies?

B cells.

What is a B cell receptor and what does it do?

Antibody bound to b-cell, bind to antigens.

What are the 2 ways in which B cells are activated?

T-cell dependent and T-cell independent.

A B cell has many copies of a BCR on its surface and is also capable of producing antibodies. What do the BCR, and the produced antibodies have in common?

Both bind to same epitope. (same colors)

Be able to describe the process of T-cell-dependent B cell activation.

- B cell binds to an epitope on an antigen using its BCR

- Entire antigen is internalized by B cell.

- Antigen is digested, fragments are combined with major histocompatibility complex ll (MHC ll).

- Antigen-MHC ll complexes moves to B cell's surface.

- B cell requires help of helper T cell to activate and produce antibodies. - Activated B cell proliferates into larger clonal population of cells.

- B cells differentiate into plasma cells and memory cells.

Purpose of plasma cells?

Produce and secrete large amounts of antibody to fight current infection.

Purpose of memory cells?

Produced for future infections with same pathogen. Contribute to accelerated, more robust response.

What is antibody class switching?

Plasma cell switches from making igM, to making another class of antibody.

Why is it important that an activated B cell be able to produce different classes of antibodies?

Different classes of antibody have different strengths.

What is the difference between T-cell independent and T-cell dependent?

Independent: antigens that activate b-cells INDEPENDENTLY without Th cells.

Dependent: antigens DEPEND on Th cells for b-cell activation.

Process of T-cell independent B cell activation.

Bind to repeating epitope on polysaccharide antigen and binds using more than one BCR.

Outcomes of T-cell dependent and T-cell independent B cell activation different?

Dependent: produce plasma and memory cells.

Independent: produce only plasma cells.

What is B-cell tolerance?

B cells are tested to see if they bind on epitopes on antigens.

immune system's way of ensuring that B cells don't mistakenly attack the body's own cells..

How does antibody-antigen binding protect the host?

Opsonization: coating.

Agglutination: clumping.

Neutralization: coating pathogen/block receptors.

Antibody dependent cell-mediated cytotoxicity: igE binding to epitopes on helminths.

Complement activation:

How does T-cell detect an antigen?

Bind to antigen fragment presented on major histocompatibility complex. (MHC)

2 classes of T cells?

Helper T cells (T h cells)

Cytotoxic T cells (T c cells)

Clusters of differentiation (CD)

Specific glycoproteins on surface.

3 types of APCs?

B cells. Dendritic cells, Macrophages.

Purpose of 3 APCs?

Bind, engulf, digest, present on MHC ll. Share info with helper T cells.

What CD molecule do Th cells express on their surface?

CD4

What is CD4 purpose?

Bind to MHC ll.

What cells communicate with and activate helper T cells?

APCs only.

How does Th cell become activated?

T cells use receptor to recognize antigen.

Confirm info from APC.

Use CD4 to bind to MHC ll.

Consequence of Th cell activation?

Proliferate and send our cytokines and get memory cells.

What CD molecule does Tc cell express on their surface?

CD8

Purpose of CD8?

Bind to MHC l.

What type of cells activate cytotoxic T cells?

All nucleated cells.

What is CTL?

Activated Tc cell.

How does Tc cell become activated?

Recognize using TCR.

Use C8 to bind to MHC l.

Kill target cell and produce perforin.

What occurs during a primary adaptive immune response?

B cells + Th expose to antigens

Activate

Plasma makes igM

Class switching

Memory cells are made.

What is antibody titer?

Amount of antibody in serum

How is the secondary response to an antigen different than the primary response?

Memory cells make antibodies quickly

Difference between active and passive immunity?

Active: we make antibodies

Passive: someone else, transfers.

passive-passed over from someone else.

Active immunity naturally + artifically:

Naturally: when sick

Artifically: vaccination

Passive immunity naturally + artifically:

Naturally: transfer from mom

Artifically: injection from donor

What is a vaccine?

Suspension / fractions of organisms used to induce immunity.

What is the purpose of vaccination??

Want memory cells.. contributes to herd immunity.

6 types of vaccines

Live

Inactivated

Subunit

Toxoid

Conjugate

Nucleic Acid

Live Vaccine

LIVE weak microbes

Mimic actual infection

1-2 boosters = lifelong immunity

Inactivated Vaccine

Microbes are killed / dead

Full immunity requires boosters

Subunit Vaccine

Antigenic fragments of microbe

fragments (unit of)

Made in lab = recombinant vaccine

Separating and purifying parts of microbe = acellular vaccine.

Boosters

Toxoid Vaccine

Used when bacterial toxin is main cause of illness.

Inactivated toxin (denatured)

Boosters

Conjuate Vaccine

help body defend against germs with capsules.

combining a piece of the encapsulated with a helpful protein, making it easier for our immune system to recognize and fight these harmful invaders.

Nucleic Acid Vaccine

Use portion of genetic material from virus or bacterium DNA/RNA.

We make antigens.

What is an adjuvant?

Chemical added to vaccine to enhance body’s immune response to antigens. (feel it stronger)

Purpose: act as irritants, cause local inflammation. response to effectively introduce antigens to immune cells. make immune system aware.

Monoclonal antibody

Why are monoclonal antibodies important for immunodiagnostics?

to detect and identifiy specific

How is a desired stock of monoclonal antibodies produced in a lab?

purified antigen

inject animal with it

take out spleen

add cancerous B cells with spleen and mix

screen to find antibody

How does agglutination reactions work?

Positive and negative result?

antibody-antigen binding

positive: clumping

negative: no clumping

Different between direct and latex agglutination

direct: needs microscope

indirect: use naked eye

What is a fluorescent-antibody test? If a patient sample were tested for the presence of a specific pathogen, what would a positive vs. a negative result look like?

monoclonal antibody combined with dye

positive: fluorescent bacteria

negative: black

What is the difference between a direct and an indirect ELISA? How does each serve to diagnose diseases? What does a positive result look like?

direct: collect pathogen, tells if they have disease, color change..

indirect: collect antibody titer, tells if they had exposure

What immune cells are involved in an anaphylactic reaction?

Basophils and Mast cells

How are Basophils and Mast cells activated to cause anaphylaxis?

Bind to constant region of IgE

2 types of anaphylactic (type l) reactions?

Localized and systemic

How are anaphylactic reactions diagnosed?

Skin tests

Cytotoxic (Type II) reactions are elicited by antigens in what form?

Whole cells. Our body fights intact cells.

What occurs during a cytotoxic reaction?

IgG and IgM binds to surface of foreign cell, complement proteins then cause cell lysis.

What ultimately is responsible for cell death of the target cell?

Complement activation.

What components of transfused blood can trigger a cytotoxic reaction?

A,B Carbs and Rh factor.

You should be able to predict if a cytotoxic reaction would occur between a specific donor/recipient pair.

Draw chart. What is missing? Cross it off.

In what scenario is there a risk factor for the development of hemolytic disease of the newborn

Why is it that differing carbohydrates on the surface of the mother’s and fetus’s RBCs does not contribute to this condition?

Mother is Rh – and fetus is Rh+.

Only if fetus has protein mother doesn’t have.

How does an immune complex (Type III) reaction result in host cell damage?

  IgG form immune complex. Gets stuck. Activate complement proteins.

How is a cell-mediated (Type IV) reaction different from the other 3 types of hypersensitivity reactions?

No antibodies involved.  

What causes host cell damage during a cell-mediated reaction?

Phagocytic immune cells and cytotoxic T cells.

What is autoimmunity?

What causes this to occur?

Immune cells attack self.

Loss of self-tolerance.

3 catergories of autoimmune diseases?

Cytotoxic (Type ll)

Immune Complex (Type lll)

Cell Mediated (Type IV)

Is there a difference between MHC molecules and HLA molecules?

No, they are the same.

Why is HLA typing important in transplant surgery?

Must be similar to be effective!

What is immunodeficiency?

Absence of sufficient immune response.

How is congenital immunodeficiency different from acquired immunodeficiency?

Congenital: Present at birth / born with defective or missing genes.

Acquired: During life as result of drugs, cancer, or infection.

How is HIV able to evade attack by the immune system?  

Latent virus

How does HIV cause immunodeficiency?

Targets Helper T Cells

If someone has AIDS would vaccination be an effective protection from other infectious diseases?

Why or why not?

No

They don’t have helper T cells. Rely on herd immunity.

What is selective toxicity?

Drug target pathogen and not harming host.

Why is selective toxicity an important aspect of antimicrobial drugs?

We elimate pathogen without hurting ourselves.  

Under what circumstances would you choose to use either a narrow or broad-spectrum antibiotic?

Narrow: you know what is causing the disease, affects specific set of microbes.

Broad: no time for treatment need to treat right away, affect many types of microbes and is impactful to us. (Always chose narrow spectrum)

What is a bactericidal drug?

Kills organism

What is a bacteriostatic drug?

Inhibits growth

5 different mechanisms of action of antimicrobial drugs?

Inhibiting cell wall synthesis

Inhibiting protein synthesis

Inhibiting nucleic acid replication

Injury to plasma membrane

Inhibiting synthesis of metabolites.

What is the outcome of a bacterium treated with a cell wall synthesis inhibitor?

Cell lysis. Bactericidal.

Why are only actively growing cells affected by cell wall synthesis inhibitors?

They are currently synthesizing – then being stopped.

What is the function of a β-lactamase enzyme?

Inhibits bridges in bacterial cell walls

Why is protein synthesis a good drug target for infections caused by bacteria

  Use different ribosome 70S. They only bind to 70S not 80S.

What is the outcome when bacterial protein synthesis is inhibited?

Bacteriostatic

What is the outcome when the bacterial plasma membrane is injured?

Cidal

What is the outcome when RNA synthesis is inhibited in a bacterium?

Cidal

What is the outcome when DNA synthesis is inhibited in a bacterium?

Cidal