Exam 1 (Lectures 3/4) Flashcards
True or False: Antibodies are glycosamines
False - glycoproteins
True or False: All the below mentioned are POSITIVE outcomes of antibody production
-Neutralize viruses and toxins
-Accelerate clearance of bacteria
-Use for clinical assays
-Use as therapies to kill tumor cells
True
True or False: Allergies, Immune Complex Disease, and Autoimmunity are NEGATIVE outcomes of antibody production
True
What’s the major difference between immunoglobulins and antibodies?
- Immunoglobulin (Ig): General term for all antibody molecules
- Antibodies: Immunoglobulins made by TERMINALLY DIFFERENTIATED B LYMPHOCYTES in response to foreign antigen
True or False: The constant region defines the isotype of the heavy chain
False - the conserved region defines isotype of heavy chain
True or False: In an antibody, both light chains and heavy chains are identical
True
What determines the heavy chain type?
The amino acid
Which part of the antibody binds to the antigen?
A. Fab Region
B. Constant Region
C. Fc Region
D. Fragment of Antigen Binding
A.) Fab Region and
D.) Fragment of Antigen Binding
Which part of the antibody forms idiotype? the isotype?
-Idiotype = The Fab Region
-Isotype = Fc Region
Fab binds to ___ antigen while F(ab)2 binds ___ antigens
1, 2
Where is the Constant Region located: the Fab Region or the Fc Region?
Fc Region
Which region of the antibody contains biological activity: the Fab region or crystallized fragment region?
Crystallized fragment region (Fc)
True or False: Opsonization and helping to lyse microorganisms are examples of biological activity carried out by the Fc Region
True
What region of the antibody is found on BOTH the heavy and light chains, is encoded in the genome, and is same between antibody molecules
The Constant Region
Which Ig is the major Ig isotype in serum and crosses the placenta?
IgG
Where is the Variable Region located?
Portion of heavy and light chain that binds epitope
IgM is secreted by plasma cells as ____ and is joined by ____ chains
pentamer; J chains
True or False: IgM binds 10 antigens at a time
False - Despite 10 F(ab) it only binds 5 antigens at a time
What is the first Ig synthesized in response to an antigen?
IgM
Which Ig is a dimer in mucus secretions and is linked by J chains?
IgA
What is the major Ig found in external secretions (saliva, sweat, tears)?
IgA
True or False: IgE has lowest serum concentration
True
True or False: IgE is an agglutinating antibody and a complement-activating Ab
False - it is NEITHER
Which Ig protects host from parasitic infections by interaction with eosinophils?
IgE
Which Ig mediates Type 1 Hypersensitivity Responses (allergies)?
IgE
Which Ig is the only to be susceptible to proteolytic degradation?
IgD
Which Ig is a marker of B Cell differentiation?
IgD
Two fates of Ig molecules?
1) Secreted (terminally differentiated B cells) 2) Anchored in the B cell membrane + acts as antigen receptor for cell
___: The inverse of the highest dilution of a substance that reacts with a fixed amount of target material
Titer
Three clinical uses of serology?
1) Obtain specific diagnosis using antibody response - 4x increase in titer
2) Screen population
3) Monitor treatment efficacy
____: Measure of the ability of a test to exclude non-diseased cases
_____: Measure of the ability of a test to identify diseased cases
Specificity: Measure of the ability of a test to exclude non-diseased cases
Sensitivity: Measure of the ability of a test to identify diseased cases
When are SPECIFIC tests most helpful?
When tests are….
positive or negative?
to rule in or rule out?
SPECIFIC TESTS are most helpful when test is (+) to rule in
Which tests is likely to identify those who do NOT have disease: Specific Tests or Sensitive Tests?
Specific Tests
True or False: PCR (RNA Amplification) is an example of sensitive tests while an at-home pregnancy tests, EIA and antigen testing are specific
PCR = specific test
Pregnancy tests, EIA, antigen = sensitive test
What test is most helpful when it’s negative (to rule out) and is likely to identify everyone with the disease?
Sensitive Tests
Screening tests should have high ____ while confirmatory tests should have high _____
sensitivity; specificity
If antibodies are so specific, why do get false positives?
Similar antigens/epitopes may cross-react
Are ELISA’s and Enzyme Immunoassay (EIA) qualitative or quanitative?
Enzyme-Linked ImmunoSorbent Assay (ELISA): Quanitative
EIA: Qualitative
True or False: ELISA are used to find antigen or antibody in patient’s serum/secretions
False - Enzyme Immunoassay (EIA) are used to find antigen or antibody in patient’s serum/secretions
True or False: Immunofluorescence Assay is good for localizing antigen using fluorescently labeled antigens
True
Direct IFA detect antigen located in the ___ while IFA detects antigen located in ____
tissue; serum
What type of Immunofluorescence Assay would you use for biopsy/peripheral blood/rabies?
Direct IFA
What type of IFA is associated with:
- Nuclear antigens (autoimmunity)
-Infectious agents
-Lupus
Indirect IFA
What are the clinical uses of Flow Cytometry?
1) CD4:CD8 ratios in HIV
2) Analyze tumor cells for markers
3) Analyze peripheral blood for % of cell types
True or False: Fluorescence Activated Cell Sorting (FAC) is used to isolate and purify specific cell populations AND sort cells for use in transplant/lab
True
True or False: Both Flow Cytometry and Fluorescence Activated Cell Sorting use fluoresceinated antibodies to measure:
1) Cell size and number
2) Density of cell surface molecules
3) Number of cells with a certain cell-surface molecule
True
What does precipitation in a secondary binding test tell you about the antigen?
What does agglutination in a secondary binding test tell you about the antigen?
Precipitation means that antigen is SOLUBLE
Agglutination means that the antigen is INSOLUBLE
____ Antibody: reacts with soluble antigen resulting in formation of insoluble precipitate
Precipitin Antibody (Ab)
What type of antibody reacts with an insoluble antigen, results in clumping
Agglutinin
What are the two types of precipitation reactions?
1) Immunodiffusion Tests (Ouchterlony Test)
2) Radial Immunodiffusion Tests
What do Ouchterlony and Radial Immunodiffusion Tests have in common? (hint: antigen)
Both use SOLUBLE antigens
True or False: Immunodiffusion Tests (Ouchterlony Test) are qualitative and used to test/ID parasitic infections
False -
While immunodiffusion tests are qualitative, they are used clinically to test/ID fungal diseases
Are Radial Immunodiffusion Tests qualitative or quantitative? Clinical uses?
Radial Immunodiffusion Tests, a type of precipitation reaction, is quantitative and used to determine [IgG isotypes] in serum
Clinical uses of Direct Agglutination?
What type of antigens are used in Direct Agglutination?
Blood Typing
Direct Agglutination reactions use insoluble antigens (e.g RBC)
True or False: In Indirect/Passive agglutination reactions, a INSOLUBLE antigen of interest is attached to a SOLUBLE antigen
False
In an indirect/passive agglutination reactions, a SOLUBLE antigen of interest is attached to a INSOLUBLE antigen
Many proteins factors in the complement system are found in the ___ as inactive (zymogens)
serum
What molecules/structures are responsible for making the zymogens for the complement system?
Liver, monocytes, macrophages
What are the major functions of the complement system?
1) Opsonization “prepare food”
2) Recruit and activate phagocytic and inflammatory cells to site of complementation activation
(anaphylatoxins)
3) Margination
4) Regulate vascular tone
_____: small MW substance that induces degranulation of mast cells and release of histamine/other vasoactive substances
Anaphylatoxins
C3a, C4a and C5a components are referred to as ____
Anaphylatoxins
C5a (strongest), C3a, C4a (weakest)
C3b and C4b act as ____, thereby tagging microorganisms, dead cells, antigens, etc. for phagocytosis by macrophages and neutrophils — which possess complement receptors (!)
opsins
What two molecules regulate vascular tone?
C2 and C2 kinin
_____: A process in inflammation that allows leukocytes to adhere to endothelium of vessel walls in preparation for movement from vasculature to site of inflammation
Margination
True or False: Margination is associated with C5a
True
____: Movement of leukocytes through a gradient toward increasing concentrations of a substance
Chemotaxis
What are two chemoattractants for WBC’s?
C5a and C3a
What is the ultimate goal of the Complement System?
Form the membrane attack
complex (MAC) which results in cell lysis.
What molecule removes Immune Complexes?
RBC’s (via CR1) - they move to the RE system (liver and spleen) and undergo phagocytosis
Opsonization describes the _____and is
mediated by complement protein______.
A. Tagging of microorganisms - C3b
B. Tagging of microorganisms – C5a
C. Directional migration of leukocytes – C3b
D. Directional migration of leukocytes – C5a
E. Regulation of vascular tone – C3b
F. Regulation of vascular tone – C5a
A. Tagging of microorganisms - C3b
What are the three activation pathways?
1) Classical
2) Alternate
3) Lectin
All three activation pathways result in the formation of _____
C3 Convertase
True or False: The complementation pathways converge at a single terminal pathway
True
If not removed, IC’s (immune complexes) tend to aggregate, enlarge, and precipitate in basement membrane of small blood vessels in the kidney glomeruli, synovium, and skin
True
C3 convertase is an important amplification step in both the
___and ___complement pathways.
alternative ; classical
True or False: A single C3 convertase can activate hundreds
of C3 molecules
True
What is the order in which the C molecules (4) are activated in the Classical Activation Pathway?
C1, C4, C2, C3
How is the classical pathway activated?
1) Antigen-antibody complexes containing IgM or IgG
C1 binds to ___ portion of the antibody, leading to its activation
Fc
What is required for C1 activation?
Simultaneous binding to TWO molecules of Fc in close proximity (either 2 molecules of IgG in close proximity to one another or 1 molecule of IgM)
Once C4b accepts C2, what does activate C1 (C1’) do?
C1’ cleaves C2 → C2a + C2b, → C4b2b Complex
In the classical activation pathway, what complex cleaves C3 into C3a and C3b?
C4b2b Complex
Once C4b2b Complex cleaves C3 into C3b and C3a, ___ binds to the membrane and ____ is formed
C3b ; C4b2b3b
What gives the classical activation pathway more control and allows for
regulation PRIOR to amplification of the pathway, to the point in which potent
inflammatory mediators are produced in abundance?
Weaker anaphylatoxins are generated first (C4a then C3a) and the more
potent one is generated last (C5a)
True or False: The Alternative Pathway functions in the presence of antibodies
False - the Alternative Pathway functions in the ABSENCE of antibodies
What activates the Alternative Pathway?
Anything that hydrolyses C3
* leukocyte proteases
* plasmin
* bacteria or bacterial products (LPS, bacterial cell wall components)
* aggregated IgA
* cobra venom factor
* Cellophane
* Water “Ticking over”
Activation of Alternative Pathway occurs via hydrolysis of ___
C3
What factor binds to C3b in the alternative pathway?
Factor B
Factor B is a substrate for Factor ___
D
What is the role of Factor D in the Alternative Activation Pathway?
Factor D cleaves B to form C3bBb (the alternative pathway C3 convertase)
The Alternative Pathway is also known as the _______
Properidin Pathway
True or False: There is a amplification loop of C3 cleavage in the properidin pathway
True
Which molecule of the alternative pathway is so unstable that it requires Factor P to stabilize it?
Properdin (Factor P) binds to C3bBb and stabilizes it
Under what conditions is there an explosive amplification of C3 cleavage in the Properidin Pathway?
When C3bBb-Properdin Complex binds and cleaves increasing amounts of C3
True or False: Binding and cleavage by C3bBb-Properdin Complex increases the amounts of bound C3b AND further stabilizes C3bnBb-Properdin?
True
C3bnBb-Properdin is also know as ______ in the Alternative Pathway, which allows for activation of terminal pathway
C5 convertase
What protein in the Mannose Binding Lectin pathway binds to TERMINAL mannose residues of proteins and polysaccharides that are only located on surface of bacteria?
Mannose Binding Lectin (MBL)
In the Manose Binding Lectin pathway, ___ is structurally homologous to C1 of classical pathway
Mannose Binding Lectin (MBL)
What is the effect of Mannose Binding Lectin binding to mannose residues on bacterial surface?
Enzymatically activates MBL for same substrate as C1’
Which pathway is responsible for formation of the membrane attack complex (MAC)?
Terminal Pathway
What does the membrane attack complex do?
Pokes holes into cell membranes
-Cell membrane damage
-Cell lysis
True or False: Once a stable C5 Convertase is formed by either activation pathway, they converge into a single terminal pathway
True
C4b2b3b (classical) or C3bnBb (alternate pathway) act to cleave what molecule?
C5
Once C5b is formed, C6-8 bind sequentially. Then, ___polymerizes and inserts itself into the cell membranes, forming a channel that allows ____
C9 ; osmotic lysis
C_-_ are terminal complement components and form the membrane attack complex (MAC)
5-9
What pathway does C1 Inhibitor (C1INH) inhibit?
Classical and Lectin
How does C1INH inhibit Classical Pathway?
Dissociation of C1r and C1s from C1q
True or False: C1INH limits the amount of time that C1’ is active in the alternative pathway
False -
C1INH limits the amount of time that C1’ is active in the classical pathway
Where are DAF or CD55 located?
Decay Accelerating Factor
- cell surface
What is the function of DAF or CD55?
Dissociates C4b2b
(classical C3 convertase)
and C3bBb
(alternative C3 convertase)
True or False: Activation of CD55 can results in loss of enzymatic pathway and inhibition of either that alternative or classical pathway
True
What pathway does Factor H inhibit?
Alternative pathway
Factor H can disassociate ____ complexes
C3bBb
Factor H competes with Factor __ for binding to C3b (surface bound)
Factor B
Following dissociation of C4b2b or C3bBb by DAF, ____ cleaves the structures, preventing them from functioning
Factor I
Serum Carboxypeptidase B is a _____ Inactivator
Anaphylatoxin
True or False: The only real difference between the Lectin pathway and the classical pathway is that
MBL is substituted for C1 complex during initiation
True
Which complement activation pathway(s) can
be activated by a bacterial infection?
A. Classical pathway
B. Lectin pathway
C. Alternative pathway
D. Classical and Lectin only
E. All three
E.
Serum Carboxypeptidase B causes proteolytic removal of terminal ___ residues and inactivates anaphylatoxins
arginine
Which molecule prevents insertion of MAC and cytolysis? How?
Vitronectin (S protein)
Binds to C5b67 complex
What molecule PREVENTS C9 polymerization? How?
CD59 - binds to C5b-8
Deficiency of C1, C4, C2, C3 or Factor I are associated with what conditions?
1) Deficiency in opsionization
2) Difficulty clearing IC’s
3) Susceptible to infx by encapsulated bactera
Difficulty handling blood borne infections with Neisseria meningitidis (gram negative) is associated with what type deficiencies?
A. C1, C2, C3, C5 deficiency
B. C6, C6, C7, C8 deficiency
C. Factor H deficiency
D. Factor I deficiency
B. Deficiency of C5, C6, C7, or C8
______ is associated with stress/trauma provoked vasodilatation and edema
usually of the skin, extremities, or GI mucosa
Type I Hereditary Angioedema
What are individuals with Type I Hereditary Angioedema deficient in ?
C1 Esterase Inhibitor (C1INH)
Which of the answers below is Factor H deficiency associated with?
A. Increased susceptibility to many bacteria
B. Increased infection by encapsulated bacteria and N. meningitis
C. Lysis of RBC/endothelial cells and hemolytic-ureimc syndrome
C. Lysis of RBC/endothelial cells and hemolytic-ureimc syndrome
Properdin deficiency is associated with: _____
A. Increased infections by encapsulated bacteria and N. meningitis
B. Increased susceptibility to many bacteria
C. Lysis of RBC/endothelial cells and hemolytic-ureimc syndrome
A. Increased infections by encapsulated bacteria and N. meningitis
MBL deficiency increases the susceptibility to MANY common bacterial infections including
1) _____
2) ____
3) ____
1) Neisseria meningitides
2) Streptococcus pneumoniae
3) Staphylococcus
aureus
Which antibody is normally found on the surface of B cells, in association with IgM, where it acts as a receptor
True
Serum half life of IgG, IgA, IgM, IgD, and IgE?
IgG = 23 days
IgA = 5.5 days
IgM = 5 days
IgD = 2.8 days
IgE = 2.0 days
Which IgG largely activates complement and have high agglutination capacity?
IgM
What two Ig’s have high neutralizing activity?
IgG and IgM
_____: The multi-molecular complex formed upon binding of antigen with its antibody
Immune complex
A serum sample is diluted 1:16 and still yields a positive response, but the next dilution higher yields a negative response. What is the titer?
16
In clinical serology tests tests, either the ___ or ___ must be known
antibody; antigen
_____: when different antigens/epitopes that are similar enough in structure, shape, charge can be bound by the same antibody
Cross Reactivity
What type of binding tests are: direct and indirect Immunofluorescence, flow cytometry, and ELISA/EIA?
Primary Binding Tests
Which test is best for determining titers?
A. ELISA
B. EIA
C. DFA
D. IFA
A. ELISA
_____: tests that allow Ag and Ab to combine and then measure amount of immune complex formed
Primary Binding Tests
Two examples of immunoassays?
1) Home pregnancy test
2) Rapid strep/rapid COVID
What molecule is a highly potent chemotactic factor for neutrophils?
C5a
What molecule is a highly potent chemotactic factor for neutrophils?
C5a
What molecule triggers formation of MAC?
A. C5b
B. C6a
C. C5a
A. C5b
True or False: Type I Hereditary Angioedema is associated with generation of bradykinin
True
What may cause the spontaneous attacks seen in Type I Hereditary Angioedema?
1) Activation of bradykinin
2) Activation of C1 by plasmin
3) Generation of C4a
What Factor competes with Factor B for binding to C3b and can dissociate C3bBb complex?
Factor H
Following dissociation of C4b2b or C3bBb by DAF, Factor ____ cleaves the structures, preventing function
Factor I
