Antigens and antibodies Flashcards by tcarlso 3

What are the group of chemicals (polysaccharide, protein etc) that the adaptive immune system recognizes?

Epitopes or determinants

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What accounts for the adaptive immune system’s specificity?

Lymphocyte having cell membrane receptors that distinguish between epitopes

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How many specificities does each lymphocyte have?

One!!

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What accounts the in lowered response time of a secondary infection/immunological memory?

Immunologic memory is due to the presence of memory cells.These cells are more sensitive to stimulation by antigen than are antigen-naive lymphocytes

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What are the three factors that abate the immune response?

Removal of antigen (no further stimulation)
Death of activated lymphocytes
Regulatory immune system

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What phospholipid is the marker for cell death?

Phosphatidyl serine on the outside of a cell membrane

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How are autoimmune diseases brought about?

When immune cells that are specific for self proteins do not undergo apoptosis during development

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What is immunogenicity?

The property of a molecule that allows it to induce an immune response.

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What are adjuvants?

Chemicals that prolong another molecule’s (like antigen) retention in the body so that a more vigorous immune response can occur

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What is antigenicity?

The property of a molecule that allows it to react with an antibody.

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What are haptens?

Small molecules that cannot induce antibody formation but can react with antibody that is specific for it, (i.e. it must be coupled to a carrier molecule in order to induce antibody formation. Therefore, an hapten is an antigen, but not an immunogen).

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What molecular weight is the dividing line between immunogenic and less immunogenic immunogens?

Molecules of >10,000 molecular weight are the best immunogens

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The (BLANK) complex the molecule, the more capable it is to be an immunogen.

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Where does immunogne processing occur?

In phagocytes

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What are the areas of the immunogen that are easy to reach and generate a strong immune response called?

Immunodominant areas

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What are the five features of immunogens that give them a strong immune response?

Size
Internal complexity
Degradability
Foreignness
Accessibility

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What are linear determinants?

Epitopes that are formed by adjacent amino acids

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What are conformational determinantss/epitopes?

are composed of amino acid residues from different parts of the protein that are brought together in space.

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T lymphocytes can only recognize what type of determinant (linear or conformational)?

Linear

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What are neoantigens?

new antigens” formed by proteolysis, phosphorylation, or exposure of new determinants through the interaction with foreign antigens

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Most antigens that the body is exposed to are of what type of chemical (polysaccharide, proteins, lipids, etc.)?

Proteins

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Where are antibodies found?

Surfaces of B lymphocytes

2. Blood plasma/tissue fluids

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How many specific antibodies can any given B cells have?

Just one

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What are the two types of immunoglobin that B lymphocytes contain/

IgM and IgD

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B lymphocytes have both IgG and IgM immunoglobin. What, therefore, must occur if a B cell needs to produce antibodies of another isotype?

Isotope switching

Blood plasma and tissue fluids contain large amounts of antibody that has been secreted from what cell type?

Plasma cells

True or false: The antibodies produced by plasma cells have only minor changes compared to the immunoglobin that is present on the plasma cells surface

True

What immunoglobin type are found on the surfaces of mast cells? What type of antibodies do these capture?

IgE--capture soluble antibodies

True or false: Secretory fluids such as mucus and milk contain do NOT antibody

False

What is antiserum?

Antibody-containing serum.

What is serum?

the fluid portion of the blood after the cellular elements have clotted

What are polyclonal antiserums?

A population of antibodies which (collectively) can bind to more than one particular antigen, since each antibody will bind different antigens

What are monoclonal antiserums?

antiserum that contains antibodies which bind to only one specific antigen

What is an antibody titer?

the reciprocal of the last dilution of antiserum that still yields a demonstrable antibody binding reaction

What are the three bands into which antibodies separate into when undergoing electrophoresis? In which band are most found?

Alpha Beta Gamma--most found

True or false: the term "immunoglobin" is synonymous with "antibody".

True

What are the two major components that antibodies are made of (hint, there are two pairs of these general structures)?

Light chains | Heavy chains

How may amino acids make up a general immunoglobin chain's domain?

~110

What are the three genes that allow for the variability of immunoglobins?

V, D, and J

In which part of the antibody are variable regions found, heavy or light chain?

Both

Heavy chains of antibodies are connected together via what type of bond?

Disulfide between C residues

What connects the two light chains of the antibody together?

Disulfide bonds between the carboxy terminus of the light chain to the VH or CH1 region of the heavy chain

The variable regions can be subdivided into what two regions?

Hypervariable region | Framework regions

What are hypoervariable regions? How many are there?

Three areas on the heavy and light chain that come together to form the antibody binding surface.

What region provides antibodies their great variability?

Hypervariable region

What type of interactions occur at the hypervariable binding site?

Transient non-covalent interactions

What antibody types have hinge regions? What are these used for?

IgG, IgA, and IgD. These are used to facilitate binding where there is a large space between different parts of an antigen

All five antibody isotypes can be expressed in two forms, which are what?

Secretory and membrane form

Secretory forms of IgM and IgA have what additional piece that allows the formation of pentamers of IgM and dimers or trimers of IgA?

A tail piece that allows the addition of a J chain

Which isotypes can only be secreted as monomers?

IgG, IgD, and IgE

What are the five classes of immunoglobin?

G (IgG), IgM, IgA, IgD, and IgE

Isotype switching allows a single antigen specificity to be used for different biological functions, which is provided by what?

different antibody constant regions

Papain digestion of antibodies results in what?

Two Fab chains, each having one antigen binding site, and one Fc fragment.

Pepsin digestion of antibodies results in what?

a single F(ab')2 fragment, with two antigen binding sites, and no surviving Fc fragment.

What does the greek letter denote in the name of an antibody?

Its class, with each class mediating a different biological effect

What do the subclasses of antibodies denote?

The order of abundance in the serum

What is the antibody in highest abundance in the human body?

IgG--70%

True or false; The secretory form of IgG is a dimer

False--monomer

Which complement pathway is IgG good at activating?

The classical complement pathway

Which IgG subclass does not activate complement?

IgG4

Which IgG subclasses can opsonize microbes? What receptor on the surface of bacteria is resonsible for this?

IgG1 and IgG3 Fc receptors for IgG

What isotype of IgG can coat target cells, such as tumor cells or virus-infected cells, to facilitate antibody-dependent cell-mediated cytotoxicity (ADCC) by natural killer cells and macrophages.

IgG1 and IgG3

What is the only immunoglobulin class capable of crossing the placenta to convey protective immunity to the fetus?

IgG

Specific receptors on the placental cells attach to the what portion of the IgG molecule to actively transport the antibody through the cells and into the fetal blood circulation?

Fc portion

What immunoglobin subclass is present in breast milk?

IgG

What is the second most highly concentrated immunoglobin isotype found in the serum?

IgM

The secretory form of IgM is of what type (monomer, dimer, trimer, etc)?

Pentamer

The pentameric structure of the IgM subclass is stabilized by what structure?

The J chain

Can the IgM subclass activate complement?

Yes

Which is better at activating complement, IgG or IgM?

IgM

(1. ?) is the predominate antibody produced in a primary immune response, whereas in a secondary immune response (2. ?) is the main antibody produced.

1. IgM is the predominate antibody produced in a primary immune response 1. In secondary immune response IgG is the main antibody produced.

Which isotype of immunoglobin can be transported across mucosal barriers into the respiratory tract or the lumen of mucosa-lined organs (example: intestines) to neutralize microbes, etc

IgA

Receptors on respiratory or intestinal epithelial cells can bind the IgA by what region, to transport it across the membrane?

Fc receptor

Where else besides mucus is IgA present?

Tears, saliva, colostrum, and milk

IgA has what structure in its secretory form (monomer, dimer, trimer etc)? In secretions?

Monomer in serum, dimer in secretions

What type of transport brings IgA outside of the mucosa?

Vesicular transport

During the process where dimeric IgA is transported through the mucosal cells, it is coupled with what protein? What does this do?

coupled secretory piece which protects the IgA from proteolytic enzymes while in the secretions and to act as a "glue" to bind it to the mucus found at mucosal sites

Secretory piece is derived from what?

epithelial cell Fc receptor that binds IgA in order to internalize it

In the serum, the ratio of IgA1 to IgA2 is (?):(?), whereas in the gut the ratio is (?):(?).

In the serum, the ratio of IgA1 to IgA2 is 4:1, whereas in the gut the ratio is 3:2.

The IgA dimer is held together by what chain?

J-chain

What is the immunogloin isotype that is found in the second to least amount in the serum?

IgE

What structural type is IgE secreted as (monomer, dimer, etc)?

Monomer

What does IgE bind to, and mediate?

Binds to cell surface receptors for IgE on basophils and mast cells to mediate allergies and anaphylaxis

Does the IgE receptor on mast cells have a high or low affinity for IgE?

High

What does IgE faciliate eosinophils with?

ADCC of certain parasitic infections

What is the immunogloin isotype that is found in the in the samllest amount in the serum?

IgD

Where is IgD primarily found?

on the surface of antigen-unstimulated B lymphocytes, along with IgM.

What is IgD important for?

the transduction of signals across the plasma membrane to result in antigen-driven B cell activation

What happens to B cells only expressing surface IgM, when exposed to antigen?

They become tolerized and do not go on to secrete antibody.

What is affinity?

The strength of binding for antigen of one antigen combining site, i.e. one arm of an antibody.

What is affinity maturation?

The average affinity for a population of antibodies will increase with repeated immunization with an antigen.

What is avidity?

The overall strength of attachment of an antibody which takes into account how many antigen combining sites the antibody has bound. For example, IgG antibodies only have two antigen combining sites with which to bind antigen, but IgM can bind up to 10 antigen combining sites.

What are allotypes?

Differences in the constant regions of antibodies (of the same isotype) between different individuals due to the presence of multiple alleles of the constant region genes in the human population.

What are idiotypes?

The collection of hypervariable regions (formed by the rearrangement of immunoglobulin gene segments) contributed by heavy and light chains to form the antigen-binding site, i.e. idiotype is the unique features of an antigen-binding site.