Lec 03: Antigens and Antibody Flashcards
Refers to:
- Any molecular structure that when introduced is capable of antibody production – immune response.
- They trigger the immune system, particularly the B lymphocytes, for the production of the antibody against the antigen.
Antigens
- Determines specificity of Antigen
- Responsible for the molecular weight of Ag.
A. Paratope
B. Epitope
C. Carrier Protein
- Epitope
- Carrier protein
- Antibody
- Antigen
A. Epitope
B. Paratope
- B
- A
Two properties of antigens
Immunogenic and antigenic
- Refers to the inherent ability of a substance to induce the specific immune response resulting in the formation of immune lymphocytes or antibodies
- Refers to the ability of the antigen to react specifically with the antibody or cell that caused it to be produced by the plasma cells
A. Immunogenicity
B. Antigenicity
- A
- B
Factors that affect immunogenicity
- Foreigness
- Molecular size
- Chemical composition
- Molecular complexity and rigidity
- Ability to be processed and presented to MHC
- The immunogen must be recognized as foreign or non-self to induce immune response.
- Depends on the composition of the immunogen
- The larger the antigen/ molecule, the more immunogenic
- Antigens that are easily phagocytized are more immunogenic.
- The more complex antigen, the more immunogenic
A. Foreignness
B. Molecular size
C. Chemical composition
D. Molecular complexity and rigidity
E. Ability to be processed and presented to MHC
- A
- C
- B
- E
- D
T or F: If the body isn’t able to recognize the antigen (non-self antigen), it will initiate an immune response until it activates the B cells and plasma cells leading to the formation of the antibodies.
True
If the body destroys self-antigens, the person develops what subset of diseases?
Autoimmune diseases
T or F: The lesser the foreignness, the greater the immune response because it is less immunogenic.
???? False teh uto-uto ka naman
The number of _______ increases proportionally with the size of the molecule (the immunogen)
Epitopes
Ideally, antigens should be greater than how many daltons for it to become immunogenic?
10,000
Daltons that has decreased immunogenicity
5000 to 1000
Refers to an incomplete antigen, can become immunogenic when coupled to a carrier protein like albumin
Hapten
T or F: Hapten does not possess antigenic properties and lacks immunogenicity because it is less than 10K daltons
False (It has antigenic properties)
Examples of haptens
Drugs (penicillin), thechol (plant oak), catechol (posion ivy)
Arrange the ff from most immunogenic to least immunogenic
Proteins
Glycoproteins
Polypeptide
Polysaccharide
Nucleic acid and lipids
Protein
Polysaccharide
Glycoproteins
Polypeptide
Nucleic Acid and Lipids
PaPaGoPakNanay ????
- Antigens that are composed of these are the most immunogenic
- ABO, Rh, Antigen
- Insulin
- Enotoxin, pneumococcal capsule
- Least immunogenic
A. Proteins
B. Glycoproteins
C. Polypeptide
D. Polysaccharide
E. Nucleic Acid and Lipids
- A
- B
- C
- D
- E
Which is better between complex protein and large repeating proteins?
Complex proteins
- Has something to do with agglutination reactions
- For precipitation
A. Particulate antigen
B. Soluble antigen
- A
- B
T or F: Particulate antigen is better than the soluble antigen
True
Two pathways involved in the presentation of MHC
T cell dependent and T cell independent
- The antigen can act on the B cells. They can have a direct effect on B cells until it will be activated into plasma cells producing antibodies
- The MHC will will present the T cells and the T cells will release interleukins leading to the activation of B cells. Once B cells are activated, they will become plasma cells until eventually, will produce antibodies against the antigen
A. T-cell independent
B. T-cell dependent
- A
- B
Define the ff per item
- Any substance that is capable of stimulating antibody production
- Any substance that can induce an immune
response (not necessarily antibody
production) - One example is hapten
- Can bind specifically to the antibody that is produced by the immune response
- Special class of immunogen that can induce an immune response leading to an allergic reaction
- Substance added to an immunogen to enhance immune response
- Added to vaccines in order to increase antibody titer and will also induce cell medated immunity
A. Antigen
B. Immunogen
C. Allergen
D. Adjuvants
- A
- B
- A
- A
- C
- D
- D
- Enhance antigen uptake of APC
- Bind to PRR to stimulate innate immunity and the release of cytokines that can
affect adaptive immunity
A. Immunopotentiators
B. Antigen delivery system
- B
- A
Classification of adjuvants
Antigen delivery system
Immunopotentiators
Antigen delivery system
- CFA, MPL, LPS, MF59
- Aluminum hydroxide, aluminum phosphate, potassium aluminum sulfate (“alum”)
- Virosome
- Stimulates T-helper and phagocytic cells
A. Aluminum salts
B. Oil-in-water emulsions
C. Microparticles
- B
- A
- C
- A
Affinity or avidity
- It refers to the strength of interaction between complex antigens.
- The combination of affinity
- The strength of single antigen-antibody bond
- The measure of the functional affinity of an antibody for the whole antigen
- The strength of the attraction between an epitope and a paratope
- Avidity
- Avidity
- Affinity
- Avidity
- Affinity
Oil-in-water emulsions
- For shingles vaccine; stimulates T cells
- Stimulates B cells
- Contains squalene which comes from Shark’s Oil that recently use for HIV vaccine development
- M TB vaccine; stimulate T cells
A. CFA
B. LPS
C. MPL
D. MF59
- C
- B
- D
- A
Familiarize the functions of antibodies
- Antibodies binds to the specific antigens that was introduced
- Fix complement
- Facilitate phagocytosis Neutralize toxins
Refers to:
- Produced by B lymphocytes or Plasma cells in response to antigenic stimulation
- Immunoglobulins or Gamma Globulins
Antibodies
T or F: There are instances that antigens are antigenic and immunogenic
True
___% of plasma proteins are immunoglobulins;; in which __% of this are polypeptides and __% are carbohydrates
20%; 86 - 98%; 2-14%
Structure of the antibody that refers to the antigen-binding site
Variable region
Two properties of antibodies
Affinity and Avidity
Functions of antibodies
- Antigens can induce immune response; B cells will be activated leading to the conduction of antibodies against the antigen that was introduced.
- Antigen-antibody complexes activate the complement system (classical pathway), triggering its antibacterial activity.
- Phagocytic cells grab the antibodies bound to the surface of foreign substances for efficient
phagocytosis.
A. Neutralize toxins
B. Fix complement
C. Antibodies bind to the specific antigens that was introduced
D. Facilitate phagocytosis
- C
- B
- D
Refers to the determinant of
the antibody–the specificity of the antibody depends on this because it is the structure that will bind to the epitope of the antigen.
Paratope
Enumerate the basic antibody structure
- Four polypeptide chains
- Hinge region
- Variable region
- Interconnection between the heavy chains through disulfide linkages; located between CH1 and CH2
- Composed of two identical light chains and two identical heavy chains; held together by covalent disulfide bonds
- One of the two major regions, located at the end of each structure
A. Four polypeptide chains
B. Hinge region
C. Variable region
- Hinge
- Four polypeptide region
- Variable region
- Where complement fixation and phagocytosis occur due to the presence of CH2 and CH3
- Antibody specificity due to the presence of the presence of the variable region with this fragment
A. Fc
B. Fab
- A
- B
The immunoglobulin can be fragmented in two fragments, which are?
Fc Fragment (Crystallizable Fragment) and Fab Fragment (Antigen-binding fragment)
Enzymes involved in the enzymatic digestion
Papain and Pepsin
Refers to the carboxyl terminal region and the constant amino acid sequence in the antibody
Constant region
Functions of different domains
- Binds with complement, specifically C1Q and
initiates the complement pathway. - Responsible for cytotropic reactions involving
macrophages, monocytes, mast cells, cytotoxic killer cells, and B cells. - Responsible for the determination of the light chain type-either Kappa or Lambda
A. CL
B. CH2
C. CH3
- B
- C
- a
Refers to when B cells produce excess light chain which results in the presence of a free light chain
Bence Jones protein or M proteins
Three gene types of the antibody
Isotype, Allotype, Idiotype
- Fragments the antibody into 2 Fab
because upon the addition of pepsin, the Fc fragment will be digested by the enzyme. - Splits the antibody into three fragments with 2 Fab and 1 Fc
A. Papain
B. Pepsin
- B
- A
Lightest among all immunoglobulins
IgG
Refers to the enzyme that has:
- Two (2) Fab – that has 2 antigen binding site (bivalent), therefore it is capable of antigen binding, precipitation, and agglutination
● The Fc portion in pepsin is destroyed.
Pepsin
Heaviest among all immunoglobulin
IgM
Refers to enzyme that has:
- Two (2) Fab – capable of antigen binding even without the Fc but cannot agglutinate or precipitate
- One (1) Fc – involve in the biologic function of Ig such as complement fixation, placental transfer of Ig, and serve as the binding site for cell
Papain
Enzyme that cannot agglutinate or precipitate
Papain
Refers to:
- Variation in the variable region of both heavy and light chain of the antibody
- This is responsible for the specificity of Ig
Idiotype
T or F: IgG, IgA, and IgD have 4 domains, as
compared to IgM and IgE, both having 5.
True
Refers:
- Classes of immunoglobulin: IgGAMDE
- Antigenic (amino acid) differences in their constant heavy region
Isotype
Refers to:
- Variation in the constant region of both heavy and light chain of Ab
- Same species, different alleles.
- Four IgG Subclasses: IgG1, IgG2, IgG3, and IgG4. Although they are all IgGs, they differ in the said regions.
Allotype
This immunoglobulin can be dimer in secretion but its blood serum form exists as a monomeric
IgA
Immunoglobulins that have a J chain that stands for joint chain or joining chain
IgA and IgM
Immunoglobulin that is pentameric
IgM
Immunoglobulins that have 2 antigen-binding sites
IgG, IgD, and IgE (they are monomeric)
How many binding sites does IgM have?
10
How many binding sites that IgA have?
2 or 4
Refers:
- Represents the sedimentation coefficient; it is measured in SVEDBERG UNITS and is associated
with analytical centrifuge or ultracentrifuge. - When subjected to centrifugation, their
sedimentation rate is listed in the table.
S value
Refers to:
● Also known as Precipitating Antibody
● Found intravascular and extravascular
● Major immunoglobulin in secondary immune response
● Coats organisms to enhance phagocytosis (opsonization)
● Mediates ADCC, neutralizes toxins and viruses
● Provides baby with immunity for first few weeks of infant’s life
IgG
Optimum reactivity of IgG
37*C
Which type of IgG cannot activate the classical pathway?
IgG4
Which IgG cannot bind to staph protein?
Ig3
Which IgG cannot cross the placenta?
IgG2
Refers to:
● Predominant immunoglobulin in secretions (secretory Immunoglobulin)
● Produced by lymphoid tissue
● Important anti-inflammatory agent in respiratory, urinary, and bowel infections
IgA
Which fragments of immobilized human IgA are able to activate the C3 in the alternative pathway?
Fab fragment
Subclasses of IgA
IgA1 and IgA2
- Mainly in serum; usually a monomer
- Predominant form in secretions and mucosal surfaces; usually a dimer
A. IgA1
B. IgA2
- A
- B
Refers to:
● Also known as Agglutinating Antibody
● React at room temperature as compared to IgG
● Due to large size, it is restricted in Intravascular Space
● Predominant Immunoglobulin in primary immune response
● Most efficient at activating the classical pathway
● First antibody that an infant makes
IgM
Refers to:
● Present on the surface of B Cells
● No definite function or role
● Heat and acid labile
IgD
Refers to:
● Mediates Type 1 Hypersensitivity (allergic) reactions.
● Fc region binds to Basophil or Mast Cells
● May also be elevated during parasitic infections
IgE
