Immunology & Serology - Lecture - 3 - Immunogens, Antigens & Vaccines - Complete

Immunology

The branch of science that deals with the study of the immune system.

Immune system

It is our body's defense system against infections, diseases, and abnormal cells

Neutrophils, Eosinophils, Monocytes, Macrophages, Basophils, Dendritic cells, T cells, B cells

What white blood cells are involved in the immune system?

Antibodies, Cytokines, Lymphokines, Organs like Bone marrow, Thymus, Spleen

What molecules or substances are involved in the immune system?

Antigen-antibody reaction

Basic principle of immunology to form an immune response

Immune response

It is the reaction of the body against antigens or foreign substances to react or fight the infection

Antigen

It is any substance with the ability to combine or recognize with an antibody

Antigen

These molecules cannot induce an immune response, unless they are an immunogen.

Immunogen

It is a substance—an antigen—that is capable of inducing an immune response

No

Yes or No

Are all antigens foreign?

Yes

Yes or No

Are bacteria, parasites, viruses, and fungi foreign substances?

Yes

Yes or No

Do pollen, dust, transplanted organs, and inhibitor cancer cells come from non-infectious sources?

Self-antigens

Antigens from our own body

Red blood cells

What is a common example of a self-antigen?

No

Yes or No

Are all antigens strong enough to cause a full immune response?

Antigenicity

It is the ability of the antigen to react specifically with the antibodies or cells it provoked

Specific reactivity

Other name for antigenicity

Immunogenicity

It is the ability to provoke an immune response by stimulating the production of antibodies, proliferation of specific T cells, or both.

Immunogen

Between an antigen and an immunogen, which can trigger an immune response?

Yes

Yes or No

All immunogens are antigens. Not all antigens are immunogens.

A

Identify blood type.

Antigen: A

Antibody: Anti-B

B

Identify blood type.

Antigen: B

Antibody: Anti-A

O

Identify blood type.

Antigen: O

Antibody: Anti-A, Anti-B

AB

Identify blood type.

Antigen: A, B

Antibody: None

Hemolytic anemia

What condition can be induced by transfusing the wrong blood type to a patient?

Yes

Yes or No

The blood group antigens, like those in the ABO system, are considered strong immunogens.

No

Yes or No

Can other antigens, like the Rh factor, always cause a robust immune response in everyone?

Yes

Yes or No

Is the ABO blood group system a strong immunogen?

Rhesus monkey

From which monkey was the Rh factor discovered?

D antigen

What antigen in Rh factor contributes to the presence of "+" and "-" in blood types? (e.g., B+, B-)

Positive

Most Filipinos are Rh (positive or negative)

Negative

Most Americans are Rh (positive or negative)

Yes

Yes or No

Foreign substances can be immunogenic or antigenic if their membrane or molecular components contain structures recognized as foreign by the immune system.

No

Yes or No

Are all foreign substances immunogenic?

Epitope

It is the basis by which the body's defense system recognizes an antigen and is seen on the cell surface

Antigenic determinant

Other name for Epitope

Epitope

It is part of an antigen that reacts specifically with an antibody or T-lymphocyte receptor

Epitope

This dictates the shape of the antibody

Epitope

This determines the precise molecular shapes or configurations recognized by B cells or the peptide sequences detected by T cells

Peptides, glycan

The cell wall of a bacteria is composed of peptidoglycan, its composition are the immunogenic parts of the bacteria since one is a protein and the other a sugar.

Amino acids

The building block of proteins

Primary, secondary, tertiary, quaternary

Different structures of proteins

Linear epitope

This type of epitope are sequential amino acids on a single polypeptide chain.

Conformational epitope

This type of epitope is composed of folding one or more polypeptide chains, bringing together amino acids that may be distant from each other.

Foreignness, Size, Chemical composition and complexity, Route, dosage, and timing, Degradability, Adjuvants

Factors affected immunogenicity

Foreignness

It is the degree to which antigenic determinants are recognized by non-self by an individual's immune system

Yes

Yes or No

The greater the difference or foreignness, the greater the immune response

Yes

Yes or No

The greater the molecular weight, the greater the immune response

No

Yes or No

Can antigens <5,000 daltons trigger antibody production or immune response?

Potential antigen

What type of antigen have molecular weights of >10,000 daltons?

Good immunogen

What type of antigen have molecular weights of 40,000 daltons?

Excellent immunogen

What type of antigen have molecular weights of 1 million daltons?

Good immunogen

What type of antigen according to molecular weight is albumin?

Excellent immunogen

What type of antigen according to molecular weight is hemocyanin?

Directly

The number of antigenic determinants on a molecule is (directly or indirectly) related to its size

Yes

Yes or No

Proteins are effective antigens because of a large molecular weight.

Yes

Yes or No

Large molecules have a lot of epitopes. The more the epitopes, the more antibodies will combine. The more antibodies, the higher the immune response.

Yes

Yes or No

The greater the complexity, the greater the immune response.

Proteins

What antigens chemical composition and complexity are the most immunogenic because they are heavy?

Polysaccharides

What antigens chemical composition and complexity are the second most immunogenic?

Lipids

What antigen chemical composition and complexity are the least immunogenic?

Nucleic acids

What antigen chemical composition and complexity is single-stranded and can become immunogenic?

Proteins

What antigen chemical composition and complexity has an increased molecular weight and structural complexity?

Polysaccharides

What antigen chemical composition and complexity is too small to function as antigen and is rapidly degraded?

Lipids

What antigen chemical composition and complexity has low molecular weight, low stability, and is relatively simple?

Nucleic acids

What antigen chemical composition and complexity has molecular flexibility?

Lipids

What antigen composition needs a combination protein to become immunogenic?

Lipoproteins

What is the only exception from lipids being least immunogenic?

Nucleic acids

Building blocks of DNA and RNA

Nucleic acids

What antigen chemical composition and complexity is variable, either immunogenic or not?

Stable

What antigen structural stability is considered a good antigen?

Not stable

What antigen structural stability is considered a poor antigen?

Poor

Totally inert molecules are (good or poor) antigens because they are unreactive and unstable.

Structural stability

This is important in cases where the goal is to elicit a patient antibody response when administering a vaccine. Vaccines must be stable for it to be long lasting and more effective.

Complexity

What factor affecting immunogenicity refers to complex proteins as better antigens than large repeating polymers such as lipids, carbohydrates, and nucleic acids?

Intravenous, Intradermal, Subcutaneous, Intramuscular, Oral

Different ways to deliver an antigen

Intravenous

What antigen delivery route is administered via the vein?

Intradermal

What antigen delivery route is administered into the skin?

Intradermal

What is the delivery route of Bacille Calmette-Guerin vaccines?

Subcutaneous

What antigen delivery route is administered beneath the skin?

Intramuscular

What antigen delivery route are most vaccines given in a 90° angle?

Oral

What antigen delivery route is very convenient but immune response is very weak because of oral tolerance?

Oral tolerance

It is the phenomenon where antigens delivered via the gastrointestinal tract are ignored by the cells of the adaptive immune system.

Yes

Yes or No

Antigens delivered orally are ignored because the gastrointestinal tract sees a lot of proteins from food intake.

If there were no oral tolerance, almost everything we ate would trigger an antibody-antigen reaction, causing an allergy.

Hence, the gastrointestinal tract ignores almost all proteins to avoid an allergic reaction for every food intake with proteins.

Antigen-antibody reaction

If people with peanut and seafood allergy ingest those (peanut, seafood), what type of reaction happens in the gut, leading to immune response?

Mast cells

When antigen-antibody reaction happens in the gut, what cells do antibodies release?

Histamine

What do mast cells release causing an allergic reaction?

Optimal dose

It is the dose that stimulates the immune system without causing harm

Too low

Antigen dose if it does not provide sufficient stimulus

Too high

Antigen dose that can lead to excessive inflammation or tolerance

Dose-response relationship

This states that as the dose of antigen increases, the immune response also increases up to a certain point. Beyond this point, the response might plateau or decline due to immune saturation or adverse effects.

Timing

Proper execution for this between doses, especially for booster shots, can enhance the strength and longevity of the immune response.

Primary immune response

What type of immune response is it if it is the initial reaction to the antigen which causes the production of antibodies and immune cells? It has slow immune response

Secondary immune response

What type of immune response is it when there is re-exposure to the same antigen and is stronger and faster due to memory cells?

Window of Opportunity

It is the time when immune response is most effective.

Window of Opportunity

Administering booster doses of additional exposes within this window can maximize immune response

Too early

Dosage timing that has not much significance since the body has not produced much of antibody reaction and there is no memory cells yet.

Too late

Dosage timing if the antibodies have already been depleted

Degradability

It refers to the immunogen's ability to be broken down into smaller fragments that can be recognized and presented by cells of the immune system

Degradability

This factor affecting immunogenicity is primarily in antigen-presenting cells.