Serology Les. 3 Mod 1

These flashcards cover key concepts and vocabulary related to the immune system, specifically focusing on antigens and antibodies.

Antigen

A genetic marker on tissues that enables the immune system to recognize self vs. non-self.

Antibody

A protein produced by the immune system in response to an antigen.

Immunogen

A substance that induces an immune response; it always elicits an antibody response.

Epitope

The specific part of an antigen that is recognized by the immune system.

ABO compatibility

The matching of blood types based on the presence or absence of A and B antigens.

Antibody Testing

Tests that identify specific antibodies in the blood to determine exposure to pathogens, like malaria.

Vaccines

Weakened or attenuated forms of antigens that elicit an immune response without causing disease.

Cross-reactivity

The reaction of an antibody with similar but different antigens.

IgM

The first antibody type produced in response to an infection, can bind up to 10 antigens at once.

IgG

The most abundant antibody type, can cross the placenta and provides long-term immunity.

IgA

An antibody found in mucosal areas, secretions like saliva, and breast milk; exists as a dimer in secretions.

IgE

An antibody associated with allergy and anaphylaxis; binds to allergens and triggers histamine release.

Cytokines

Chemical signals released by immune cells that mediate inflammation and fever.

How is an antigen defined from a genetic perspective?

An antigen is a genetic marker (or determinant) on tissue that allow the immune system to recognize a cell as part of the body.

How is an antigen defined when it is introduced as a foreign substance?

It is a substance (such as a virus, bacteria, fungus, or vaccine) that has not been encountered before and elicits the immune system to respond by producing antibodies.

What distinguishes an immunogen from a general antigen?

While an antigen may not always provoke an immune response, an immunogen is specific and will always generate a response by stimulating antibody production.

What is an epitope?

An epitope is a specific piece on an antigen that determines its identity and is the part the body responds to; it acts like a signal (e.g., a wagging finger) that triggers an immediate reaction.

What are the chemical structural characteristics of an antigen?

Antigens are typically proteins or polysaccharides that are hardy (not easily destroyed), complex, and possess a high molecular weight (MW).

What is the most important aspect of an antigen's physical nature?

Being foreign is the most important characteristic; it must be non-self to be an effective antigen and trigger an immune response.

What is the primary function of an antibody?

The main function is to combine with an antigen; antibodies can also combine with complement proteins.

What is the general structure of an antibody molecule?

Antibodies are glycoproteins composed of 2 heavy chains (which determine the class: IgG, IgA, IgM, IgE, or IgD) and 2 light chains (lambda or kappa).

How does the Fab region of an antibody function?

The Fab (Fragment Antibody) region is the top part of the Y-structure where antigen binding occurs; it contains variable chains that change to fit specific antigens.

How does the Fc region of an antibody function?

The Fc (Fragment Complement) region is the lower part of the Y-structure responsible for effector functions; it binds to complement proteins only if an antigen-antibody bond exists.

How many antigens can monomers, dimers, and pentamers bind?

Monomers can combine with 2 antigens, dimers with 4, and pentamers with 10 at a time.

What are the characteristics of IgG?

IgG is a monomer and the most abundant antibody in serum (\approx 75\%); it can cross the placenta and provides long-term immunity.

What are the characteristics of IgA?

IgA is found in secretions (saliva, tears, mucus), exists as a dimer held by a J-chain, has 2 subclasses, and cannot cross the placenta.

What makes IgM unique in structure and production?

IgM is the first antibody produced in a response; it is a large pentamer that binds 10 antigens and is strictly intravascular because it cannot cross the placenta.

What is the primary role of IgE?

IgE is a monomer that mediates allergic reactions and parasite responses; it binds to mast cells and basophils to trigger the release of histamine.

Where is IgD typically found and what is its association?

IgD is a monomer associated with B lymphocytes and is frequently seen in conjunction with IgM.

What happens during the Lag Phase of antibody synthesis?

This is the initial period after exposure where the immune system recognizes the antigen but produces little to no antibodies.

What happens during the Log Phase of antibody synthesis?

During this phase, antibody production increases rapidly and antibody titers rise exponentially.

What occur during the Plateau and Decline phases of the immune response?

Antibody levels stabilize during the Plateau Phase and then gradually decrease toward zero during the Decline Phase.

What is an Anamnestic Response?

It is a secondary immune response where memory B lymphocytes facilitate a quicker and stronger response (primarily IgG) upon re-exposure to the same antigen.

Cooperative Interaction requires:

Specific cellular elements, cell products, and nonlymphoid elements

Nonspecific immune elements include or require

Mononuclear phagocytes

Secondary lymphoid tissues in mammals are

Lymph nodes -this is one of the secondary lymphoid tissues that provide a unique microenvironment for the initiation and development of immune responses

Genetically different individuals of the same species are refered to as

Allogenic (“Allo-” means different, other or another)

What can antigens be composed of?

Large polysaccharides, proteins, and glycoproteins and glycolipids

The least important characteristic of an antigen is

the presence of large repeating polymers (or multicarbon or protein structures)

IgE has the shortest half-life. why?

Because it works during allergic reactions

The characteristic associated with IgG is

It increases in infectious diseases, collagen disorders, and hematological disorders.

The characteristic associated with IgD is

It is primarily a cell membrane

Specificity

The ability of an antibody to combine with one antigen instead of another

Affinity

The strength of a bond between a single Epitope and an individual combining site. i.g. Antigen -”Does it love me?” Antibody -”Oh yes I do! Now bond with me!”

Avidity

The total functional strength of all interactions between an antibody and an antigen. i.g. Antibody -”Hey, I know you’re cousin! C’mon, you’re bonding with me along with the others! The more, the merrier!”

Immune Complex

The noncovalent combination of antigens with its respective specific antibody

The types of bonding that are involved in the antigen-antibody reactions

1. Hydrophobic bond (The major one done) 2. Hydrogen bonds 3. Van der Waals