Ag and Ab Flashcards by Angela Marcelino

macromolecules that is capable triggering an adaptive immune response by inducing formation of antibodies or sensitized T cells of an immunocompetent host

Immunogen

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can evoke an immune response

Immunogen

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substance that reacts with ab or sensitized T cells but may not evoke an immune response

Antigen

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can only bind sensitized T cells or antibody, not capable of sensitizing T and B cells

Antigen

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Ability to induce a humoral and/or cell mediated immune response

immunogenicity

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ability to combine specifically with the final products of the immune response

antigenicity

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ability of Ag to react specifically with a free Ab or membrane coupled BCR

antigenicity

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active regions of immunogen that binds to antigen-specific receptors on lymphocytes or to secreted antibodies

Epitope

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binds either to Tcell receptor and antibodies

epitope

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determinant site which are recognized by Bcells/Tcells

epitope

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a substance that is non-immunogenic but it can react with the products of a specific immune response with no antibody formation

Hapten

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non-protein and low molecular weight (less than 10,000) that could never induce an immune response when administered by themselves unless it coupled to a carrier molecule

hapten

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has the property of antigenicity but not immunogenicity

hapten

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Factors influencing immunogenicity

Foreignness
size
chemical composition and complexity
route, dosage, and timing
adjuvants

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the more different the composition, the greater the response induced

foreignness

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t/f - all immunogens are considered as antigens but not all antigens are considered immunogens

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derived from the same individual

autoantigen

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derived from the same species

alloantigens

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derived from different species (gives increased response)

heteroantigen

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Ag found in unrelated plants and animals, cross react with Ab of another

Heterophile antigens

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the larger the MW, the more immune response induced

size

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amount of potent Ag

> 10,000 Daltons

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example of a good immunogen and how many daltons

Albumin - 40,000 daltonse

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example of excellent immunogen and how many daltons

Hemocyanin - 1 million daltons

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most immunogenic

protein

2nd most immunogenic

polysaccharide

non-immunogenic

lipids and nucleic acids

examples of microbes

- capsules - cell wall - toxins - viral capsids - flagella

example of non microbes

- pollen - egg whites - RBC surface molecules - serum proteins - surface molecule from transplanted tissue

effective routes of Ag

intravenous and intraperitoneal

stronger stimulus than subcutaneous or intramuscular

intradermal

t/f: general rule for route, dosage and timing - the smaller the dose, the less response

substance added to vaccine and less immunogenic molecules (hapten) to increase the immune response

Adjuvants

fxn of adjuvants

- stimulates T cells: enhance cell mediated immunity - stimulate B cells: enhance humoral response - stimulate phagocytosis

adjuvant that is water in oil emulsion of Mycobacterium/ Bordatella pertussis/ MTB

Complete Freund's Adjuvant

adjuvant for animals

Complete Freund's Adjuvant

Adjuvant that stimulates B-cells

Lipopolysaccharide

adjuvant that stimulates phagocytosis

Alum adjuvant

adjuvant for humans

Alum adjuvant

adjuvant from shark oil, for HIV vaxx

Squalene

Ag which can directly stimulate the B cells to produce Ab without the requirement for T cell help

T independent Ag

Example of T independent Ag

POLYSACCHARIDES - Pneumococcal polysaccharides - lipopolysaccharide - flagella

those that do not directly stimulate the production of Ab without the help of T cells

T-dependent Ag

example of T-dependent Ag

PROTEINS - Microbial protein

glycoproteins that recognize and bind to a particular Ag with very high specificity

Antibodies

made in response to exposure to the Antigen

Antibodies

t/f: each antibody has at least 2 identical sites that bing antigen: Antigen binding sites (epitope) will bind to the paratope (antibody binding site)

antibodies belong to a group of serum called___ which are proteins in nature

IgG

what is the pH of Ab during Electrophoresis

8.6

in what band does the immunoglobulin primarily appear in at pH 8.6 during electrophoresis

Alpha band

example of alpha band

albumin (cathode)

fastest band to migrate in electrophoresis

alpha band

lightest band to migrate in electrophoresis

gamma band

what immunoglobulin activate the classical pathway

IgG and IgM

general functions of immunoglobulins

1. Neutralize toxic substances (especially those that are produced by pathogens like bacteria, viruses, parasites and fungi) 2. Facilitate phagocytosis and kill microbes 3. Combine with antigens on cellular surfaces and thereby cause the destruction of these cells either extravascular (outside the blood vessels within the mononuclear- phagocyte system, also known as Reticular endothelial system (RES))) or intravascularly

primary organ where antigens are destroyed

spleen

postulated that certain cells had specific surface receptors for antigen

Paul Ehrlich

Occurred once antigen was introduced, it would select the cell with proper receptor, combination would take place and receptors would break off and enter the circulation as antibody molecules

Ehrlich's side chain theory

New receptors would form in place of those broken off and enter the circulation as antibody molecules

Ehrlich's Side Chain theory

Antibody producing cells are capable of synthesizing a generalized type of antibody and when contact with an antigen occurs, the antigen serves as a mold or template and alters protein synthesis so hat antibody with specific fits is made

template theory

who proposed the template theory

Felix Haurowitz

Most accepted theory for antibody diversity

Clonal Selection

independently supported the idea of clonal selection process for antibody formation

Niels Jerne and Mcfarlane Burnet

The key premise is that individual lymphocytes are genetically programmed to produce one type of immunoglobulin and that a specific antigen finds or selects those particular cells capable of responding to it, causing to proliferate

Clonal Selection

worked on Immunoglobulin G (IgG)

- Gerald Edelman - Rodney Porter

* Consist of 4 polypeptide chains * Subdivided into 2 Heavy chain (large chain) and 2 Light chain (L chain)

Basic Structure of Ab

A flexible Y-shaped molecule with four protein chains

Monomer

2 identical light chains of an antibody

Kappa or Lambda chain

the antibody chains are held together by what bonds

- non-covalent forces - disulfide bonds

first approximately 110 amino acids ate the amino-terminal end

Variable domain

the H chain are unique to each class and give each immunoglobulin

constant region

immunoglobulins

- γ H chain: IgG (gamma) - α H chain: IgA (alpha) - ε H chain: IgE (epsilon) - δ H chain: IgD (delta) - μ H chain: IgM (mu)

Refers to the heavy chain that determine the Ig class

Isotype

Minor variations of these sequences that are present in some individuals but not others

Allotype

The aminoterminal ends of both L and H contain these regions, which are essential to the formation of the antigenbinding site

idiotype

variable portions of each chain are unique to a specific antibody molecule.

idiotype

Possess both constant and variable regions, it is the same for all immunoglobulins

light chain

ratio of K:L

2:1

% of Kappa in the ig

65%

% of Lambda in the Ig

35%

Discovered through Bence Jones Proteins which are light chains produced by a malignant plasma cell from the urine of Multiple Myeloma patients

Light chains

Found in between CH1 and CH2 and known as the flexible region

Hinge region

what amino acid causes the flexibility of the hinge region

Proline

Regions or section in an Ig molecule

Domain

2 domains: VL (variable light) and CL (constant light)

1 light chain

specific to each Ig - 4 domains: 1 VH (variable heavy) and 3 CH (constant heavy)

1 Heavy chain

domain of IgE

domain of IgA

who proposed the papain and pepsin digestion

- Alfred Nisonoff used pepsin - Porter’s work was based on the use of the proteolytic enzyme papain

ig taht is a pentamer

IgM

ig that is a dimer

IgA

● Cleaves the Ig above the hinge region ● 3 fragment: 2 Fab + 1 Fc

Papain digestion

● Cleaves the Ig below the hinge region ● 2 Fragments: 1 Fab + 1 Fc

Pepsin digestion

fragmentation of monomer that is derived from the enzyme of a papaya

Papain

fragmentation of monomer that is derived from the enzyme of a Hog's stomach

Pepsin

■ Basic immunoglobulin structure ■ Examples: IgG, IgD, IgE, IgA1 (most) ■ It has 2 binding site (2 valence)

Monomer

■ Secretory component or piece of IgA2 ■ It prevents the enzymatic degeneration of enzyme among secretions ■ It has a J chain (Joining chain) at the center ■ 4 valence = 4 binding sites

Dimer

■ It has more than 2 monomer ■ Example: IgM (Malaki) it is a pentamer ■ 10 valence = 10 binding sites ■ also has a J chain (the center)

Polymer

Ag and Ab Flashcards

(99 cards)