Immunology Exam 2 Flashcards
Lymphocyte that is part of humoral immunity
B lymphocyte
Lymphocyte that is part of cell mediated immunity
T lymphocyte
These cells can recognize antigens without specific antigen receptors
Natural killer cells
Three common types of processes for B and T lymphocyte maturation
- Proliferation
- Expression
- Selection
Where antigen-independent lymphopoiesis occurs
Bone marrow
Site of maturation for B lymphocytes
Bone marrow
This CD marker signals to regulate B cell development and activation
CD19
This CD marker is thought to be involved in B cell activation
CD20
Important B cell CD Markers:
Receptor for complement breakdown component
CD21
Important B cell CD Markers:
Found on activated T and B cells; receptor for interleukin-2 (IL-2); it is a growth factor made by T cells
CD25
Important antigen that is found on all nucleated cells
MCH I
Important antigen that interacts with Th cells; is present on all stages of B lymphocytes except plasma cells
MHC II
CD marker that is found on all hematopoietic cells and is involved in activation
CD45R
Basic unit construction of an antibody contains what type and how many chains?
2 Heavy chains and 2 Light chains
Maturation sequence of a B lymphocyte
- Lymphoid stem cell
- Pro-B cell
- Pre-B cell
- Immature B cell
- Mature B cell
Also known as Pro-B Cell
Progenitor B Cell
This maturation stage of a B lymphocyte is committed to the formation of mu; the IgM heavy chain
Pro-B cell
AKA
Progenitor B Cell
During this stage of maturation of B lymphocytes the bone marrow stroll cell stimulates the lymphoid stem cell to become a B cell. This is the first recognizable cell in the B-cell line.
Pro-B cell
The formation of the mu heavy chains signal the beginning of this stage of maturation for B lymphocytes
Pre-B cell
Also known as Pre-B Cell
Preliminary B-Cell
During this stage of maturation for B lymphocytes, the cell is committed to the formation of light chains
Preliminary B-Cell
AKA
Pre-B Cell
What forms the Pre-B receptor to stimulate proliferation and further maturation?
mu heavy chains and surrogate light chains
B cell maturation:
This stage sees the completion of IgM molecule on the cells surface.
Immature B cell
B cell maturation:
In this stage of maturation, mu is no longer in the cytoplasm.
Immature B cell
B cell maturation:
In the immature B cell stage, what is the cell committed to the formation of?
IgD
about what percentage of B cells are eliminated due to self-reacting?
About 90%
If the B cells are not eliminated via apoptosis due to self-reacting, where do they go to continue maturation?
Spleen
Definition:
Cell self-destruction
Apoptosis
The B cell receptor is the co-expression of ____ and ____
IgD and IgM
TRUE OR FALSE:
IgM and IgD have the same antigen specificity
TRUE
The BCR is seen during which stage of B cell maturation?
Mature B cell
Where are plasma cells found?
Bone marrow and secondary follicles
Function of plasma cells
Production of antibodies
What is required in order for B cells to form memory cells?
Protein antigen
Produces antibodies
Plasma cell
Expression of IgM and IgD
Mature B cell
Starts forming mu chain
Pro-B cell
Antigen-dependent lymphopoiesis
Activated B cell
Expression of IgM only
Immature B cell
1st recognizable B cell
Pro-B cell
Has a long life span; found in secondary follicles
Memory B cells
Formation of IgD
Immature B cell
Starts forming lights chains
Pre-B cell
This cell produces cytokines
T helper lymphocyte
This cell kills altered cells
T cytotoxic lymphocyte
Percentage of peripheral blood lymphocytes that are B cells
10-15%
Where T cells mature
Thymus
Lymphocyte precursor for T cells
Thymocytes
Percentage of peripheral blood lymphocytes that are T cells
60-80%
What drives T cell maturation?
Chemokines
T cell marker involved in T cell acitvation
CD2
Complex of proteins that delivers the signal to T cell interior upon TCR-AGN recognition, alpha and beta chains
CD3
CD marker known as T-cell maker
CD5
This marker on T cells creates rosettes when mixed with sheep RBCs and is used to detect and identify T cells.
CD2
TRUE or FALSE:
Thymocytes lack both CD4 and CD8
TRUE
Name of the first cell in T cell maturation
Double-Negative T cells (thymocytes)
In this stage of T cell maturation, both CD4 and CD8 are expressed
Double-Positive T cells
What is completed during the Double-Positive T cells maturation phase?
CD3:TCR complex
What happens if T cells show a weak recognition of MHC 1 and peptide?
A mature CD8+ T cell forms
What happens if T cells show a weak recognition of MCH II and peptide?
A mature CD4+ T cell forms
What happens if there is no recognition by the T cell of MHC and peptide?
Apoptosis
The negative selection process for T cells determines tolerance to _____
Self
Estimated amount of T cells that are CD4
~2/3
Estimated amount of T cells that are CD8
~1/3
What activates T cells?
Antigens
Type of memory cells produced by CD4 T cells
T helper memory cells
Type of memory cells produced by CD8 T cells
T cytotoxic memory cells
Estimated percentage of CD4 cells that become T regs
5-10%
What CD markers do T regulatory cells possess?
CD4 and CD25
Purpose of T regulatory cells
Maintain self-tolerance and exert active immune suppression
Location of T cells in the lymph nodes
Paracortex
Location of T cells in the spleen
Central PALS
Location of B cells in the lymph nodes
Cortex
Location of B cells in the spleen
Marginal PALS
These cells are found mainly in the spleen and peripheral blood
Natural Killer cells
Percentage of peripheral blood lymphocytes that are natural killer cells
10-15%
TRUE or FALSE:
Natural Killer cells contain either T or B cell markers
FALSE - they generally do not have T or B cell markers
What are natural killer cells believed to be derived from?
Double Negative Thymocytes with gamma and delta chains
This cell is considered a transitional cell bridging the natural and acquired immune responses.
Natural Killer cell
This CD marker is the receptor for the Fc portion of IgG on Natural Killer cells
CD16
This CD marker is the main Natural Killer marker
CD56
This cytokine activates NK cells in to lymphokine-activated killer cells (LAK)
Interleukin-2 (IL2)
This cell kills diseased/infected and cancerous cells
Natural Killer cells
TRUE or FALSE:
Natural killer cells kill cells with reduced MCH I expression
TRUE
The ability for natural killer cells to lyse cells with reduced MHC I expression is known as
Antibody-Independent Cytotoxicity
What CD marker is used on natural killer cells for antibody-coated cells to bind to?
CD16
CD16 on natural killer cells is a receptor for which antibody class?
IgG
What other cell types can perform Antibody-dependent cytotoxicity like natural killer cells? (3)
Monocytes
Macrophages
Neutrophils
Antibody-independent cytotoxicity
Natural Killer cells
Step with CD4 and CD8
Double Positive Stage
Step with either CD4 or CD8
Mature stage
Produce cytokines when activated
T helper cell
Step with neither CD4 nor CD8
Double Negative Stage
Has CD4 and CD25 markers
T Regulatory cell
Kills diseased/infected cells when activated
Cytotoxic T cell
How often does the spleen filter our blood?
4-5 times a day
These are the backbone of T cell activation
Antigen Presenting Cells
Viral antigens that present to both CD8 and CD4 cells are known to be __________
“Cross-presenting”
All nucleated cells have what MHC class?
MHC I
These lymphocytes act against changed self-antigens (viruses, intracellular microbes, tumors)
Cytotoxic T lymphocytes AKA CTLs AKA Tc lymphocytes
TRUE or FALSE:
The initial binding of Tc cells with APCs is non-specific
TRUE
What complex and marker bind with the MHC 1?
TCR-CD3 and CD8
What toxins are released from CTLs?
Perforin and Granzymes
Purpose of perforin
Destroys cell wall
Purpose of granzymes
Apoptosis
How are activated T helper lymphs important in humoral immunity?
They help B cells produce antibodies
How are activated T helper lymphs important in cell-mediated immunity?
They help T cytotoxic cells activate
T-dependent antigens are made of ______
Protein
T-independent antigens are ____-______
Non-Protein (typically carbohydrates)
TRUE or FALSE
Non-protein antigens produce a weaker response due to no production of memory cells
TRUE
These molecules stabilize binding and allows time for the TCR to “scan” the peptide antigen
Adhesion molecules
What are the Th cell subsets?
Th1
Th2
T-Reg
This Th cell subset occurs in response to intracellular microbes (cell-mediated immunity)
Th1
This Th cell subset occurs in response to helminths and allergens (humoral immunity)
Th2
This Th cell subset exerts active immune suppression to reduce immune response to avoid chronic inflammation
T-Reg
What are the different types of T-Reg cells?
tTreg and pTreg
This T-Reg cell is thymus derived
tTreg
This T-Reg cell is peripheral derived
pTreg
T cell that deals with cell-mediated immunity
T helper 1
T cell that deals with humoral immunity
T helper 2
T cell that deals with suppressing the immune system in order to avoid overactive immune response
T reg
Cells that T regs inhibit
Th1, Th2, and APCs
This T cell enhances the activity of Tc cell, NK cells, and antigen presentation
T helper 1
This T cell enhances the activity of antibody formation, allergic response, anti-parasitic response, and antigen presentation
T helper 2
This subset of T helper cells is driven by IL-9 and is a major player in the development of allergic pathologies, especially asthma
T helper 9
This interleukin stimulates cell proliferation and is proven to prevent apoptosis
IL-9
This T helper subset is a pro-inflammatory cell
T helper 17
This T helper subset is influenced by IL-21 and IL-6 and participates in the development of antigen-specific B-cell immunity. Located in the follicular areas of lymphoid tissue
T follicular helper cell
This interleukin causes proliferation and differentiation of B cells
Interleukin-2
B cells proliferate in to:
Plasma cells and memory cells
What type of Th subset develops in response to intracellular microbes?
T helper 1
What type of Th subset develops for helminths and allergens?
T helper 2
What type of antigen is referred to as T-dependent antigen?
Protein
What type of antigen is referred to as T-independent antigen?
Carbohydrate
What is the main antibody produced during the primary immune response?
IgM
What is the secondary immune response is also known as?
Anamnestic
What is the primary antibody produced in the anamnestic immune response?
IgG
Immunogen stimulates cells expressing specific BCR or TCR
Monoclonal activators
Also known as Superantigens. Typically derived from bacteria. Bind without being processed; outside of the peptide-bind groove.
Oligoclonal activators
Superantigens can activate up to ____% of Th cells
20%
Capable of inducing cell division in high percentages of T or B cells regardless of their antigen specificities
Mitogens
What are mitogens?
Polyclonal activators
This lymphocyte activator is typically plant proteins
Polyclonal activator
Polyclonal activator of B cells
Lipopolysaccharide
Most common polyclonal activator of both T and B cells
Pokeweed mitogen
Polyclonal activators of T cells
Concanavalin A and Phytohemagglutinin
How is the super antigen able to activate T helper cells?
Binds TCR and MHC II without being processed
What are the 5 classes of immunoglobulins?
IgG, IgM, IgA, IgD, and IgE
Most abundant immunoglobulin in serum
IgG
Where most antibodies are found in serum protein electrophoresis
Gamma band = “gamma globulins”
Basic unit of an antibody
Monomer
Number of polypeptides in basic structure of antibody
Four
Types of polypeptides in basic structure of antibodies
Heavy chains (2) and Light chains (2)
Fragments immunoglobulin in to 3 different pieces
Papain
Proteolytic enzyme from papaya
Papain
Important effector functions of antibodies
Opsonization and Complement fixation
What is included in the Fc portion of an immunoglobulin?
2 pieces of heavy chain which crystallized at 4C
What is included in the Fab portion of an immunoglobulin?
1 heavy chain and 1 light chain linked by a disulfide bond
Purpose of Fab portion of immunoglobulin
Antigen binding
Fragments immunoglobulins in to 2 pieces
Pepsin
Digestive enzyme found in the stomach that breaks down proteins to amino acids
Pepsin
Antigen binding fragment produced by pepsin
F(ab’)2
2 units produced from an immunoglobulin when cleaved by pepsin
F(ab’)2 and Fc’
TRUE or FALSE:
The Fc portion produced when pepsin cleaves an immunoglobulin is bigger than the Fc portion produced when Papain cleaves an immunoglobulin
FALSE- the Fc portion produced from papain cleavage is bigger.
Found in urine of multiple myeloma patients
Bence Jones proteins
Types of Light Chains
Kappa and Lambda
Ratio of kappa to lambda
2:1
Which classes of heavy chains have subclasses?
IgG and IgA
How many subclasses are there for IgG?
Four
How many subclasses does IgA have?
Two
Antibody types:
More commonly refers to the constant region of heavy chain
Isotype
Antibody types:
Variants between individuals within a species
Allotype
Antibody types:
Source of immense diversity. Variations in variable regions.
Idiotype
Where is the hinge region located on immunoglobulins?
Heavy chain - between Ch1 and Ch2
What is located on the Ch2 domain (in most cases) that helps the Fc receptors on phagocytes recognize the Fc unit?
Carbohydrate
Complement binding site for immunoglobulins
Ch2
Activation of complement results in:
Lysis of microbes and host cells
Percentage of IgG in serum
70 - 80%
Molecular weight of IgG
150,000
What determines the IgG subclass?
The number and position of the disulfide bridges
Immunoglobulin that provides immunity for newborn by crossing the placenta
IgG
Least efficient IgG subclass to provide immunity to newborn by crossing the placenta
IgG2
Immunoglobulin that fixes complement
IgG
Most efficient IgG subclass at fixing complement
IgG3 - due to a larger hinge region
IgG subclass that is a poor mediator of complement fixation
IgG4
Immunoglobulin that opsonizes antigen for enhanced phagocytosis
IgG
Immunoglobulin that neutralizes toxins and viruses by diffusing into extravascular spaces (tissues)
IgG
Immunoglobulin that is utilized in agglutination and precipitation reactions in the lab
IgG
Why is IgM better for agglutination reactions?
It is larger
Why is IgG better for precipitation reactions?
It moves through the gel easier
Molecular weight of IgM
900,000
Percentage of Immunoglobulins in serum that are IgM
~10%
Half-life of IgM
10 Days
Half-life of IgG
23-25 Days
Immunoglobulin that is a pentamer
IgM
Where is the monomer form of IgM found?
Surface of B cells
What links the 5 IgM monomers to form the pentamer?
J chain (joining chain)
Number of binding sites on IgM pentamer
10
Where is IgM found?
Intravascular pool
Immunoglobulin that cannot cross the placenta
IgM
Best immunoglobulin for triggering the classical complement pathway
IgM
Why is IgM the most efficient immunoglobulin for agglutination?
It has multiple sites and is a large molecule
4 Mechanisms used by antibodies to combat infections
Neutralization, Opsonization/phagocytosis, Antibody Dependent Cell Cytotoxicity (ADCC), Complement (C’)
Name the different light chains
Kappa and Lambda
What is a monomer?
The basic structure of immunoglobulins - 2 light chains and 2 heavy chains
Which antibody is a great opsonin?
IgG
Which antibody is great at activating complement and agglutination?
IgM
Site of production for IgA
Mainly in MALT
Where are IgA secreting plasma cells found?
Sub-epithelial tissues
Subclasses of IgA
IgA1 and IgA2
Where is IgA1 found?
Serum
Location of IgA2
Mucosal surfaces (GI, urogenital, and respiratory tracts) and body secretions
TRUE or FALSE:
IgA is a pentamer
FALSE- IgA is a dimer (IgM is a pentamer)
The structure of IgA2 includes:
2 IgA monomers, a J chain, and a secretory component
Purpose of the secretory component on IgA2
- Facilitates the transport of IgA to mucosal surfaces
- Makes the dimer more resistant to enzymatic digestion
Where is the secretory component precursor found?
On epithelial cell
Purpose of secretory component precursor?
Binds dimer and transports it across the epithelial barrier to mucosal surfaces (known as transcytosis)
Immunoglobulin that protects mucosal surfaces by neutralization, opsonization (weak), and complement activation (poor)
IgA
What removes IgA and antigen?
Ciliated epithelial cells
Percentage of IgA in serum
10-15%
Predominant immunoglobulin in external secretions
IgA
Oral vaccine used against polio vaccines
Sabin vaccine
Immunoglobulins that have a very low concentration in serum
IgD and IgE
Concentration of IgD in serum
<0.001%
Half-life of IgD
1 - 3 Days
Function of IgD
Naive B cell antigen receptor (part of B cell maturation)
Where is IgD found?
On the surface of naive B cells
Least abundant immunoglobulin in serum
IgE
Immunoglobulin that has no complement fixation, no agglutination, no opsonization, and does NOT cross the placenta
IgE
Which immunoglobulin is important in host defense against parasitic infections?
IgE
Immunoglobulin responsible for allergic reactions
IgE
The Fc portion of IgE will attach to high affinity Fc receptors on which cells only?
Basophils and Mast cells
Antigen binds to how many IgE molecules before causing a cascade of events?
2 Adjacent IgE molecules
TRUE or FALSE:
IgD recruits PMNs and eosinophils to the area of an acute inflammatory response that it triggers
FALSE- IgE triggers an acute inflammatory response and recruits PMNs and eosinophils to the area
Most abundant Ig in serum
IgG
Building blocks for immunoglobulins are found on which chromosomes? (3)
14, 2, and 22
Chromosome 14 contains the building blocks for which part of immunoglobulins?
Heavy chains
Chromosome 2 contains the building blocks for which part of immunoglobulins?
Kappa light chains
Chromosome 22 contains the building blocks for which part of immunoglobulins?
Lambda light chains
Heavy chain gene groups
Constant, Variable, Diversity, and Joining
Purpose of constant gene
Codes for Mu, Gamma, Delta, Epsilon, or Alpha
How many different variable genes are there for heavy chains?
At least 51 genes
How many different diversity genes are there for heavy chains?
At least 27 genes
How many different joining genes are there for heavy chains?
6
Light chain gene groups
Constant, Variable, and Joining
Number of different light chain variable genes
32
Number of different light chain joining genes
5
Difference between light chains and heavy chains regarding their genes
Light chains do not have a diversity gene
Light chain rearrangement always starts with ______
Kappa
What starts lambda light chain transcription?
A nonfunctional kappa chain
Term for only 1 kind of light chain made at a time
Allelic exclusion
What will stimulate B cells to class switch?
A protein antigen
Antibodies as Reagents:
What are antibodies used to detect?
- Microorganisms
- Cell antigens and antibodies
Antibodies as Reagents:
Type of antibody that is heterogeneous
Polyclonal
Source of polyclonal antibodies
Animal or human
Problems associated with polyclonal antibodies
Cross-reaction and reagent variability (not specific to any particular antigen)
Antibodies as Reagents:
Type of antibody that is homogeneous
Monoclonal
Antibodies as Reagents:
All the antibodies came from the same B cell clone making is specific
Monoclonal antibody
Advantages of monoclonal antibodies
- Permanent
- Reproducibility
- Defined specificity
Disadvantages of monoclonal antibodies
- Cost
- Narrow reactivity range
Therapeutic agent used to treat 20-30% of breast cancer patients
Herceptin
Therapeutic agent used to treat Rheumatoid Arthritis and Crohn’s disease
Inflixmab and adalimumab
Therapeutic agent used to treat Non-Hodgkin lymphoma
Rituzimab
Therapeutic agent used to treat Colorectal cancer and head and neck cancers
Cetuximab
Therapeutic agent used to treat B lymphoma and Non-Hodgkin lymphoma
Ibritumomab tiuxetan and tositumomab (antibody + radioactive substances)
Ig most associated with mucosal membranes
IgA
Ig involved in allergic reactions
IgE
Ig that is important in parasitic infections
IgE
Location of most proteins production
Liver
3 different complement pathways
- Classical
- Alternative
- Lectin
How is the Classical complement pathway activated?
Antigen-antibody combination
How is the alternative complement pathway activated?
On microbial surfaces
How is the lectin complement pathway activated?
Microbial polysaccharides
___ plays an essential role in all three complement pathways
C3
Ways the Classical complement pathway is activated
- Immune complexes (aby/agn complexes)
- CRP
- Few microorganisms
Which immunoglobulins activate the classical complement pathway?
IgG1, IgG2, IgG3, and IgM
Order of components in classical complement pathway
C1, C4, C2, C3, C4, C5, C6, C7, C8, C9
Three main stages in classical complement pathway
- Recognition unit
- Activation unit
- Membrane attack complex
Recognition unit in classical complement pathway
C1
What does C1 recognize on IgG?
CH2
What does C1 recognize on IgM?
CH3
Classical Complement Pathway:
C1 cleaves C4, which part of this cleave attaches to the cell membrane?
C4b
Classical Complement Pathway:
C4b attaching to the membrane after C1 cleaves C4 is known as:
1st amplification step
Classical Complement Pathway:
What binds to C4b and is cleaved by C1?
C2
Classical Complement Pathway:
What part of the C2 cleave is bound to C4b?
C2a
Classical Complement Pathway:
C4bC2a is the first enzymatic complex. What is it known as?
C3 convertase
Classical Complement Pathway:
What is included in the 2nd amplification step on the classical complement pathway
C3 convertase cleaves C3 into ‘a’ and ‘b’ fragments
Classical Complement Pathway:
Powerful opsonin
C3b
Classical Complement Pathway:
What is formed when C3b bonds with C3 convertase?
C5 convertase = C4b2a3b
Classical Complement Pathway:
C3 convertase
C4b2a
Classical Complement Pathway:
C5 convertase
C4b2a3b
Classical Complement Pathway:
Cleaves C5
C5 convertase = C4b2a3b
Classical Complement Pathway:
Membrane Attack Complex components
C5b6789
Classical Complement Pathway:
Purpose of the membrane attack complex
Punches holes in the cell membrane
How many C9s are included in the MAC?
10-17
What part of complement can lyse only RBCs?
C5b678
What part of complement can lyse any cell?
C5b6789
Importance of C3a
- Anaphylatoxin-
- Releases histamine
- Dilates blood vessels
- Contracts smooth muscles
- Allows vascular fluid leaks
Importance of C3b
-Strong opsonin
C4a activity
Anaphylatoxin (weaker than C3a and C5a
C5a activity
Major attractant and strong anaphylatoxin (100x stronger than C3a)
Activation of this complement pathway does not require antibody
Alternate Pathway
Complement pathway that is a component of the natural defense
Alternate Pathway
What is the Alternate Complement Pathway also known as?
Properdin system
What is properdin?
A serum protein
What parts of the classical complement pathway are not included in the alternate complement pathway?
C1, C2, and C4
What starts the alternative complement pathway?
C3 spontaneously hydrolyzes to “tickover” formed C3b
What protects host cells from “accidental” activation by the alternative complement pathway?
High levels of sialic acid
Alternative complement pathway:
What makes up C3 convertase?
C3bBb
Alternative complement pathway:
What cleaves Factor B to form Bb?
Factor D
Alternative complement pathway:
What binds with C3 convertase to stabilize it?
Properdin
Alternative complement pathway:
What makes up C5 convertase
C3bBbP3B
TRUE or FALSE:
After the alternative complement pathway completes cleaving C5, the pathway is identical to the classical pathway.
TRUE
What is “tickover”?
Spontaneous hydrolysis of C3 to C3a and C3b
What activates the alternative complement pathway?
Microorganisms
What 4 serum proteins are involved in the activation of the alternative complement pathway?
C3, Factor B, Properdin, and Factor D
What activates the lectin complement pathway?
Polysaccharides that bind to lectin
What are lectins?
Proteins that bind to carbohydrates
What complement pathway is a link between innate and acquired immune response?
Lectin Pathway
Lectin Complement Pathway:
What is structurally similar to C1qrs?
MBL (Mannose-binding lectin)
Lectin Complement Pathway:
What 3 enzymes make up MBL?
MASP-1, MASP-2, and MASP-3
Lectin Complement Pathway:
Which MBL enzyme takes the active role of cleaving C4 and C2?
MASP-2
Lectin Complement Pathway:
Where does the lectin pathway intersect the classical pathway?
C3 convertase
Complement:
What are most control proteins aimed at halting?
C3b
Regulators of Complement:
Soluble inhibitors
- C1INH
- Factor H
- Factor I
- S protein
Regulators of Complement:
Surface inhibitors
- DAF (CD55)
- MAC-inhibitory protein (CD59)
Regulators of Complement:
Role of C1 inhibitor
Blocks initiation of pathways
Regulators of Complement:
How does C1 inhibitor (C1INH) block the initiation of the classical pathway?
Binds to C1q causing C1r and C1s to dissociate
Regulators of Complement:
How does C1INH block the initiation of the lectin pathway?
Inhibits MBL-MASP-2 from binding with C4 and C2
Regulators of Complement:
What will result from having a deficiency in C1INH?
Hereditary angioedema
Regulators of Complement:
A deficiency in this inhibitor leads to excessive cleavage of C4 and C2
C1 Inhibitor
Regulators of Complement:
Purpose of Factor H in the classical pathway
Binds C3b making it vulnerable to inactivation by Factor I
Regulators of Complement:
Purpose of Factor H in the alternative pathway
Binds C3b preventing binding to Factor B
Regulators of Complement:
This inhibitor inactivates C3b when bound by Factor H
Factor I
Regulators of Complement:
This inhibitor inactivates C4b with help from C4-binding protein (C4BP)
Factor I
Regulators of Complement:
Another name for S protein
Vitronectin
Regulators of Complement:
Purpose of S protein
Interacts with C5b67 to prevent it from binding to cell membranes
Regulators of Complement:
Inhibitor also known as CD55
Decay-Accelerating Factor (DAF)
Regulators of Complement:
This inhibitor is present on peripheral blood cells, endothelial cells, and fibroblasts
DAF
aka
CD55
Regulators of Complement:
Purpose of CD55
Dissociates components of C3 convertase
Regulators of Complement:
When C3b or C4b are bound to DAF, they are vulnerable to inactivation by which inhibitor?
Factor I
Regulators of Complement:
This inhibitor protects cells from bystander lysis.
DAF
Regulators of Complement:
What results from a deficiency of Decay-Accelerating Factor?
Paroxysmal nocturnal hemoglobinuria
Regulators of Complement:
Immune deficiency found in RBCs that are deficient in CD55 and CD59 causing RBCs to be vulnerable to bystander lysis. Patients with this deficiency have a chronic hemolytic anemia
Paroxysmal nocturnal hemoglobinuria
Regulators of Complement:
Binds to C8 and prevents insertion of C9
CD59
AKA
MAC-inhibitory protein
Regulators of Complement:
This inhibitor is found on host cells and inhibits the formation of the MAC
MAC-inhibitory protein
AKA
CD59
Complement Receptors:
This receptor is present on a number of cells - mainly peripheral blood cells; binds to C3b, iC3b, and C4b; and works with Factor I to degrade C3b
CR-1
AKA CD35
Complement Receptors:
- Receptor for C3b degradation products
- Found on B cells and dendritic cells
- Involved in B cell stimulation
- Also a receptor for Epstein-Barr virus
CR-2
AKA CD21
Complement Receptors:
Patients without these receptors are prone to recurrent infections
CR-3 and CR-4
Complement Receptors:
Mediates transport of immune complexes to the liver/spleen
CR-1
How are complement components measured?
- Nephelometry
- ELISA
Laboratory tests measure the _______, not the _________ of components.
Laboratory tests measure the presence, not the function of components.
What measures total complement activity?
Total hemolytic complement (CH50)
Which components of complement are acute phase reactants?
C3 and C4
Autoimmune disorders that occur due to elevated complement levels
- Early SLE
- Rheumatoid arthritis
Infections that occur due to elevated complement levels
- Viral hepatitis
- Acute rheumatic fever
What percentage of patients without C4 develop systemic lupus erythematosus (SLE)?
90%
Deficiences in what 3 complement components leads to reduced clearing of immune complexes; causing tissue damage?
C1, C2, and C4
RBCs are deficient in DAF and CD59 resulting in chronic hemolytic anemia
Paroxysmal nocturnal hemoglobinuria
A deficiency in C1INH causes and increase in vascular permeability (edema)
Hereditary angioedema
Deficiencies in C1qr, C4, and C2 causing lupus-like disease
Early complement deficiencies
Deficiencies in C5, C6, C7, and C8 will have recurrent infections from what bacteria?
Neisseria
