Immunity and Autoimmunity Flashcards
1
Q
Define
Clonal expansion
A
the process by which daughter cells arise from a parent cell. When B-cells undergo this process, many copies of that B cell are produced that share affinity with and specificity of the same antigen
2
Q
How does genetic predisposition contribute to RA?
A
Genetic predisposition results in presentation of CPA on HLA and recognition by CD4 T cells; inflammatory environment promotes T cell activation
3
Q
Describe the steps of B-cell proliferation and the early stages of T-cell dependent immunity
A
- T- and B-cells interation; selection step 1
- Outer follicle and differentation for germinal centre, plasma cells and memory; selection step 2
- Germinal centre; mutation; selection; differentiation; selection step 3
- Maintenance of memory; selection step 4
4
Q
Describe somatic hypermutation including the segregation between the dark and light zones
A
5
Q
Describe the life of a B-cell including its survival in the bone marrow
A
6
Q
What are the two types of light chains?
A
Kappa (κ)
Lambda (λ)
7
Q
Definition
The portion of the amino (NH2) terminal of an antibody’s heavy and light chains having a variable amino acid sequence
A
Variable region
8
Q
What four things can happen to lymphocytes that are too self-reactive?
A
Deletion (cell death)
Anergy (cell silencing)
Receptor editing
Exhaustion
9
Q
• Naïve B cells express Ig__ and Ig__ on their surface, both with the same VH/VL combination.
A
• Naïve B cells express IgM and IgD on their surface, both with the same VH/VL combination.
10
Q
Fibroblast-like (Type B) synoviocytes in RA respond to inflammation by producing what?
A
- Cytokines (e.g. IL-6, IL-8, MIF, M-CSF, GM-CSF, TNF)
- Chemokines to attract inflammatory cells
- Matrix degrading enzymes such as matrix-metalloproteinases (MMPs) which lead to cartilage degradation
- Factors that promote local bone destruction
- Factors that inhibit bone formation activity
11
Q
Are Rheumatoid arthritis and Lupus systemic or local autoimmune diseases?
A
Both systemic
12
Q
What are the treatment options for RA?
A
- NSAIDs (Non-Steroidal Anti-Inflammatory Drugs
- DMARDs (Disease Modifying Anti-Rheumatic Drugs)
- Methotrexate – a folate analogue that interferes with cellular metabolism, causes cells to release adenosine, and this inhibits lymphocyte proliferation and cytokine expression
- Hydroxylchloroquine – antimalarial
- Low dose prednisone (glucocorticoids/steroids)
- Biologics: Monoclonal antibodies
- Anti-TNF
- Anti-IL-6
- Small molecule inhibitors
- Jak STAT inhibitors
13
Q
Definition
an interleukin that acts as both a pro-inflammatory cytokine and an anti-inflammatory myokine
A
IL-6
14
Q
True or False
The heavy chain undergoes VDJ recombination
A
True
15
Q
What is the most common isotype of Ig?
A
IgG
16
Q
What is the function of a healthy synovium?
A
Facilitates movement between non-deformable structures within joint (e.g. bone/cartilage surfaces)
17
Q
What are the most predominant lymphocyte in RA synovium?
A
T cells are the predominant lymphocyte in RA synovium:
- CD4+ (helper) T cells are most prevalent
18
Q
Definition
a biological mechanism that changes a B cell’s production of immunoglobulin from one type to another, such as from the isotype IgM to the isotype IgG.
A
Class switch recombination (CSR)
19
Q
What are the 2 distinct cell populations in the healthy intima?
A
80%: Fibroblast-like synoviocytes (Type B synoviocytes)
20%: Macrophage-like synoviocytes (Type A synoviocytes)
20
Q
True or False:
CSR occurs at the light chain locus only and requires the enzyme AID
A
False
CSR occurs at the Heavy chain locus only and requires the enzyme AID
21
Q
Define
TNFα
A
a cell signaling protein (cytokine) involved in systemic inflammation and is one of the cytokines that make up the acute phase reaction. It is produced chiefly by activated macrophages, although it can be produced by many other cell types such as CD4+ lymphocytes, NK cells, neutrophils, mast cells, eosinophils, and neurons
22
Q
Definition
a long-term autoimmune disease in which the body’s immune system becomes hyperactive and attacks normal, healthy tissue. Symptoms include inflammation, swelling, and damage to the joints, skin, kidneys, blood, heart, and lungs
A
Lupus
23
Q
How many chains does an Ig molecule have?
A
4 (2 heavy, 2 light)
24
Q
What is the order of serotype genes in the constant region of a Ig?
A
IgM, IgD, IgG, IgE, IgA
25
# Define
Autoantibodies
antibodies (immune proteins) that mistakenly target and react with a person's own tissues or organs
26
How do environmental triggers lead to RA?
Environmental trigger causes post-translational modification (citrullination) of selfpeptides → these are now potential autoantigens (citrullinated peptide antigens; CPA)
27
# Definition
cells of the immune system found in primary and secondary lymph follicles of the B cell areas of the lymphoid tissue. They are not derived from the bone-marrow hematopoietic stem cell, but are of mesenchymal origin
Follicular dendritic cells
28
True or False
The light chain undergoes VDJ recombination
False
The light chain undergoes VJ recombination
29
# Definition
a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies
Antigen
30
How Do Cytokines Target Class Switch Recombination in B cells?
31
What is the main tissue target for inflammation in RA?
Synovium
32
# Define
Follicular dendritic cells
cells of the immune system found in primary and secondary lymph follicles of the B cell areas of the lymphoid tissue. They are not derived from the bone-marrow hematopoietic stem cell, but are of mesenchymal origin
33
Describe the process of humanising a monoclonal antibody by CDR grafting
34
Why is immunological tolerance falliable?
1. Not all self-antigens are in the bone marrow or thymus, spatially and/or temporally
2. B-cells need a degree of self-reactivity to signal successful rearrangement and indeed to signal for continued survival
3. Self-reactive B-cells may encounter their antigen in an inflammatory context
35
How does AID cause somatic hypermutation?
AID introduces point mutations into the V regions of the genes of GC B-cells
These may cause amino acid replacements in the V genes, affecting the abilit of Ig/BCR to bind antigen
They may improve or reduce affinity or cripple the Ig completely, or do nothing
36
# Define
Anergy
the functional silencing of self-reactive cells so they become non-responsive to stimulation. Appears to be the fate of less high affinity anti-self B-cells
37
How do polymorphisms in SLE genes involved in the immune clearance of apoptotic particles and nucleic acids contribute to SLE?
Polymorphisms in genes involved in the immune clearance of apoptotic particles and nucleic-acid– containing immune complexes (orange) may induce the enhanced activation of pDCs and autoreactive B cells, leading to the production of type I interferon (IFN) and the expansion of autoreactive effector cells, respectively.
38
# Define
Exhaustion
T-cells particularly, are rendered non-functional after extensive proliferation in the face of an undiminishing antigen load
39
B-cells need intructions from ____________ to proliferate and differentiate
B-cells need intructions from **CD4 T-cells** to proliferate and differentiate
40
What cells influence the outcome of class switch recombination?
T-cells and/or the antigen
41
# Definition
the killing of self-reactive cells, appears to be the fate of high affinity anti-self. E.g. activation-induced cell death (AICD)
Deletion
42
# Definition
antibodies (immune proteins) that mistakenly target and react with a person's own tissues or organs
Autoantibodies
43
How do polymorphisms of SLE genes involved in innate immunity contribute to SLE?
Polymorphisms in genes involved in innate immunity (green) regulate the induction of, as well as the response to, type I IFN.
44
# Definition
an antibody isotype that makes up about 1% of proteins in the plasma membranes of immature B-lymphocytes where it is usually co-expressed with another cell surface antibody called IgM
IgD
45
# Definition
antibodies that are made by identical immune cells that are all clones of a unique parent cell. They can have monovalent affinity, in that they bind to the same epitope (the part of an antigen that is recognized by the antibody)
Monoclonal antibodies
46
# Definition
a cellular mechanism by which the immune system adapts to the new foreign elements that confront it (e.g. microbes), as seen during class switching
Somatic hypermutation (SHM)
47
Which Ig exists as a pentamer? Which as a dimer?
IgA is a dimer
IgM is a pentamer
48
# Definition
the part of an antigen molecule to which an antibody attaches itself
Epitope
49
Why is IFN stimulated in Lupus?
Type I interferon normally activates the antiviral response.
Nucleic acids in circulation or in the cytoplasm, which shouldn’t usually be there, act as danger-associated molecular patterns (DAMPs). These are detected by sensor proteins, like pattern recognition receptors (PRRs) which include Toll-like receptors (TLRs).
These activate signal transduction pathways that culminate in the transcription of the type I IFN genes.
50
# Define
Antigen
a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies
51
What enzyme(s) mediate V(D)J recombination?
RAG 1&2
52
True or False
VDJ segment is unaffected by CSR
True
53
# Definition
a rare type of immune cell that are known to secrete large quantities of type 1 interferon (IFNs) in response to a viral infection. They circulate in the blood and are found in peripheral lymphoid organs.
Plasmacytoid dendritic cell (pDC)
54
How does IL-6 contribute to RA?
* Pro-inflammatory cytokine
* Involved in fever and acute phase response
* In RA, produced by macrophages, synovial fibroblast-like synovial cells, T cells
* Increases acute phase response in liver (systemic inflammation)
* Induces immunoglobulin production by B cells
* Promotes differentiation of TH17 cells
* Induces cytokine production by synovial fibroblasts and macrophages
* Promotes osteoclast differentiation via induction of RANKL
* Found at high levels in RA synovial fluid and serum
55
How does JAK-STAT signaling mediate the action of IL-6?
1. Ligand binds to receptor
* JAK autophosphorylates the receptor
2. STAT binds to phosphorylated receptor
* JAK phosphorylates STAT
3. Phosphorylated STAT is released & dimerises with another phosphorylated STAT
* STAT dimer translocates to cell nucleus where it binds to DNA, initiating gene transcription
56
# Define
Phage display
a laboratory technique for the study of protein–protein, protein–peptide, and protein–DNA interactions that uses bacteriophages (viruses that infect bacteria) to connect proteins with the genetic information that encodes them
57
# Define
Monoclonal antibodies
antibodies that are made by identical immune cells that are all clones of a unique parent cell. They can have monovalent affinity, in that they bind to the same epitope (the part of an antigen that is recognized by the antibody)
58
How do inflammatory cytokines contribute to SLE?
Inflammatory cytokines strongly stimulate further maturation of self-reactive B cells and contribute to organ damage
59
What enzyme(s) mediate somatic hypermutation?
Activation Induced Cytidine Deaminase (AID)
60
# Define
Central tolerance
also known as negative selection, is the process of eliminating any developing T or B lymphocytes that are reactive to self. Through elimination of autoreactive lymphocytes, tolerance ensures that the immune system does not attack self peptides.
61
What is the function of synovial cells?
* Produce collagens and fibronectin
* Provide nutrients
* Produce lubricants
62
# Define
Constant region
The portion of the amino acid sequence of an antibody's heavy or light chains that determines the class of the antibody and does not vary within a given class
63
# Definition
a natural mode of immune response exhibited by the adaptive immune system of mammals. It ensures that a single antigen is recognized and attacked through its overlapping parts, called epitopes, by multiple clones of B cell
Polyclonal response
64
Why is the constant region of an Ig important?
It determines the effector functions of the Ig.
Each isotype has a different role to plat
65
# Define
IL-6
an interleukin that acts as both a pro-inflammatory cytokine and an anti-inflammatory myokine
66
# Define
RAG enzymes
plays important roles in the rearrangement and recombination of the genes encoding immunoglobulin and T cell receptor molecules
67
# Definition
the genetic variations or differences in the constant regions of the heavy and light chains
Isotype
68
What are three methods that can be used to bypass mouse Ig genes to make human mAbs?
1. Make a mouse that uses human Ig genes
2. Humanisation via isolation from Ag-specific B-cells: Abs from HIV-infected individuals
3. Antibody discovery and affinity maturation using phage displays
69
What type of bond connects the two heavy chains of a Ig molecule?
Disulphide bond
70
Describe the cross-talk between synoviocytes during inflammation
71
# Definition
a type of antibody produced by the immune system. If you have an allergy, your immune system overreacts to an allergen by producing this antibody type
IgE
72
# Definition
A hybrid cell used as the basis for the production of antibodies in large amounts for diagnostic or therapeutic use. They are produced by injecting a specific antigen into a mouse, collecting an antibody-producing cell from the mouse's spleen, and fusing it with a tumor cell called a myeloma cell
Hybridomas
73
# Definition
white blood cells that are also one of the body's main types of immune cells. They are made in the bone marrow and found in the blood and lymph tissue
Lymphocyte
74
What are the function of Type A and Type B synoviocytes?
**Type A:** Clearance of debris in joint, recognition of immune complexes, present antigens, initiate inflammatory responses (cytokine release)
**Type B:** Joint lubrication, produce collagen and fibronectin (cell adherance molecules)
75
How can monoclonals be humanised?
76
What happens to the Macrophages (Type A synoviocytes) in RA inflammation?
* “Activated phenotype”:
* Increased phagocytosis
* Increased antigen presentation to CD4+ T cells
* Major source of:
* Cytokines (e.g. TNF, IL-1β, IL-6, IL-18, MIF)
* Chemokines to attract inflammatory cells
77
# Define
IgE
a type of antibody produced by the immune system. If you have an allergy, your immune system overreacts to an allergen by producing this antibody type
78
# Define
IgM
one of several isotypes of antibody (also known as immunoglobulin) that are produced by vertebrates. It is the largest antibody, and it is the first antibody to appear in the response to initial exposure to an antigen
79
What is the overall process of making monoclonal antibodies?
80
Where are B-cells located during changes to their affinity and Ig class?
Germinal centres
81
Draw a graph showing the difference between primary and secondary exposure to an antigen in terms of serum Ig levels, affinity and predominant Ig serotype
82
# Define
IgD
an antibody isotype that makes up about 1% of proteins in the plasma membranes of immature B-lymphocytes where it is usually co-expressed with another cell surface antibody called IgM
83
# Definition
a diverse set of microbial molecules that share a number of different general “patterns,” or structures, that alert immune cells to destroy intruding pathogens
PAMPs
84
What are the advantages of using a phage display to make human mAbs?
Can recover specificities to anything...not limited by self/non-self, or species conserved antigens
85
Why do B-cells initially make IgM but then change?
Pentameric IgM allows low affinity antibody to bind antigen. As affinity increases via clonal selection and SHM, IgM can be replaced with IgG, IgA or IgE with their specialised effector functions
86
# Definition
secondary rounds of V-J gene segment rearrangement to generate a revised BCR that is no longer self-reactive
Receptor editing
87
# Define
Variable region
The portion of the amino (NH2) terminal of an antibody's heavy and light chains having a variable amino acid sequence
88
# Definition
one of several isotypes of antibody (also known as immunoglobulin) that are produced by vertebrates. It is the largest antibody, and it is the first antibody to appear in the response to initial exposure to an antigen
IgM
89
What happens to immune complexes in autoimmune diseases?
IC can accumulate on the walls of fine blood vessels, triggering activation of granulocytes and causing tissue damage
90
# Define
Tertiary lymphoid sites
ectopic lymphoid organs that develop in non-lymphoid tissues at sites of chronic inflammation including tumours
91
# Definition
also known as negative selection, is the process of eliminating any developing T or B lymphocytes that are reactive to self. Through elimination of autoreactive lymphocytes, tolerance ensures that the immune system does not attack self peptides.
Central tolerance
92
What cells produce TNF in RA?
In RA, produced by activated macrophages (predominantly), activated fibroblast-like synoviocytes and other cells types (e.g. T cells)
93
How does adaptive immune system activation contribute to Lupus?
94
# Definition
the unique mechanism of genetic recombination that occurs only in developing lymphocytes during the early stages of T and B cell maturation. It involves somatic recombination, and results in the highly diverse repertoire of antibodies/immunoglobulins and T cell receptors (TCRs) found in B cells and T cells, respectively
V(D)J recombination
95
What type of specialised cells secretes Igs?
Plasma cells
96
# Definition
plays important roles in the rearrangement and recombination of the genes encoding immunoglobulin and T cell receptor molecules
RAG enzymes
97
# Define
Lupus
a long-term autoimmune disease in which the body's immune system becomes hyperactive and attacks normal, healthy tissue. Symptoms include inflammation, swelling, and damage to the joints, skin, kidneys, blood, heart, and lungs
98
# Define
Transfectoma
A myeloma cell into which immunoglobulin genes have been transfected
99
# Define
Pathogen recognition receptor (PRR)
proteins capable of recognizing molecules frequently found in pathogens (the so-called Pathogen-Associated Molecular Patterns—PAMPs), or molecules released by damaged cells (the Damage-Associated Molecular Patterns—DAMPs)
100
Genetic predisposition results in evasion of \_\_\_\_\_\_\_\_\_selection, and subsequent activation, of selfreactive B and T cells in SLE
Genetic predisposition results in evasion of **negative** selection, and subsequent activation, of selfreactive B and T cells in SLE
101
How many loci encode for the immunoglobulin genes?
3
102
What does TNF release do in RA?
103
# Definition
T-cells particularly, are rendered non-functional after extensive proliferation in the face of an undiminishing antigen load
Exhaustion
104
# Define
CD4 T-cells
a type of T cell that play an important role in the immune system, particularly in the adaptive immune system. They help the activity of other immune cells by releasing T cell cytokines. These cells help suppress or regulate immune responses
105
# Define
Class switch recombination (CSR)
a biological mechanism that changes a B cell's production of immunoglobulin from one type to another, such as from the isotype IgM to the isotype IgG.
106
How do TH17 and T regulatory cells contribute to RA inflammation?
**TH17 cells:**
* Subset of CD4+ T cells that express IL-17
* Recruitment and differentiation induced by IL-6, IL-23 and IL-1
* Express RANKL, the essential differentiation factor for osteoclasts (the bone resorbing cell); promotes bone erosion
* IL-17 induces expression of other pro-inflammatory cytokines and also RANKL in other cell types; promotes inflammatory response
**T regulatory (Treg) cells:**
* Subset of T cells identified by CD25+ , FoxP3+
* Normally act to suppress immune/inflammatory response
* In RA: cells are present within synovial tissues but are not functional (e.g. reduced expression of cytokines IL-10, IL-4) – _have lost their regulatory (anti-inflammatory) capability_
107
True or False:
TNF is a common target for monoclonal antibodies to treat RA
True
108
How do B-cells contribute to RA inflammation?
* Presence and distribution of B cells is variable among RA patients:
* Likely depends on stage of disease
* Responsible for antibody production in response to T cell activation by antigen presenting cells.
* Local production of autoantibodies (e.g. rheumatoid factor, anti-citrullinated peptide antibodies (ACPA), anti-collagen type II)
* Present antigen to CD4+ T cell and secrete cytokines
* Source of RANKL - required for osteoclast differentiation, contributing to bone resorption.
109
True or False:
Class switch recombination changes the constant region without changing antigen binding
True
110
# Definition
the functional silencing of self-reactive cells so they become non-responsive to stimulation. Appears to be the fate of less high affinity anti-self B-cells
Anergy
111
What factors contribute to the altered post-transcriptional regulation (citrullination) that triggers Rheumatoid arthritis?
Environmental factors (periodontitis, smoking, microbiome)
Epigenetic modification
Susceptibility genes
112
What are the two parts of the synovium and what are their features?
**Intima:**
* 1-3 cell layers deep
* Cells = synoviocytes
**Subintima**
* Contains blood vessels, lymphatic vessels and nerves, but few cells
113
What cell type are prevalent mediators of inflammation within the RA joint?
Fibroblast-like (Type B) synoviocytes)
114
True or False:
All autoimmune disease antibodies are pathogenic
False
In some autoimmune diseases it is not the antibody that drives the condition
115
CSR is deletion recombination mediated by S-S recognition and requires double stranded breaks in the DNA that are generated by AID and repaired by \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
CSR is deletion recombination mediated by S-S recognition and requires double stranded breaks in the DNA that are generated by AID and repaired by **nonhomologous end joining (NHEJ)**
116
What happens to immunecomplexes in normal people?
IC are usually cleared by phagocytosis, facilitated by the complement system
117
# Define
Switch (S) region
conserved nucleotide motifs upstream from gene segments that encode the constant regions of antibody heavy chains; the site of double-stranded breaks
118
The genetic predisposition of SLE involves many alleles involved in what?
Reduction of tolerance
119
Where do immune complexes accumulate in Lupus?
Glomeruli in kidneys and many other sites
120
What does transciptome data show about people with Lupus?
They have a interferon signature of genes that are downregulated compared to healthy controls
121
In what ways can mAbs be changed to improve therapeutic effect?
• Improve potency • Improve functionality • Longer half-life • Tissue distribution • Solubility • Reduce Cost
122
Describe the pathogenesis of RA
123
What happens to the synovium in RA?
* Cell proliferation (hyperplasia) causing the intima to expand → up to 12 cells
* Infiltration of inflammatory cells into the subintima: macrophages, T cells, B cells, neutrophils (less common)
* Formation of new blood vessels (neovascularisation)
* Ectopic lymphoid neogenesis
* Deposition of fibrin in active disease – citrullinated fibrinogen may contribute to localized ACPA
124
True or False:
Organ damage in lupus patients is a major predictor of mortality
True
125
How do you make antibody production long-lived?
Fuse the population of antigen-reactive B cells with an immortal cell line (longevity, in vitro growth, high level antibody secretion)
126
# Definition
a cell signaling protein (cytokine) involved in systemic inflammation and is one of the cytokines that make up the acute phase reaction. It is produced chiefly by activated macrophages, although it can be produced by many other cell types such as CD4+ lymphocytes, NK cells, neutrophils, mast cells, eosinophils, and neurons
TNFα
127
Why can Naive B-cells express IgM and IgD on their surface?
Alternate splicing from the one mRNA transcript that starts from the promoter that is upstream of the VH segment.
128
# Define
Epitope
the part of an antigen molecule to which an antibody attaches itself
129
How do B-cells solicit help from T-cells?
* Activated B cells process and present antigen to T cells via MHCII and express ICOSL
* Activated T cells “see” antigen and co-stimulation (ICOSL), provide “help”
* Help = CD40L (proliferation and AID inducing) and interleukins (differentiation, CSR)
* CD40 activates B cells by activating the NFkB signaling pathway
* In the absence of CD4 help, B-cells do nothing in a T cell dependent response
130
Describe the Relationship Between Antigen and Immunoglobulin Isotype Switching T-cell derived Signals Target AID to particular S-regions thus directing CSR
131
CDRs _______ are encoded in the germline, where as CDR _____ is created during rearrangement
CDRs **1 & 2** are encoded in the germline, where as CDR **3** is created during rearrangement
132
# Definition
A myeloma cell into which immunoglobulin genes have been transfected
Transfectoma
133
True or False:
Somatic hypermutation changes the constant region without changing antigen binding
False
Somatic hypermutation affects **antigen binding** without changing **constant region**
134
# Definition
a type of antibody. Representing approximately 75% of serum antibodies in humans, it is the most common type of antibody found in blood circulation
IgG
135
What type of cells are found within a germinal centre?
B-cells
CD4 helper T-cells
Follicular dendritic cells
136
# Definition
an abnormal layer of fibrovascular tissue or granulation tissue. Common sites include over the cornea, over a joint surface (as seen in rheumatoid arthritis), or on a prosthetic heart valve
Pannus
137
# Define
Activation induced cytidine deaminase (AID)
causes mutations that produce antibody diversity, but that same mutation process leads to B cell lymphoma
138
How do you use a phage display to make human mAbs?
**Step 1:** Make a library of phage expressing all possible VH + VL genes, using human B cells as template (NB: ScFv)
**Step 2:** Screen library on target antigen. Select phage binders. Introduce random mutations in V genes. Select stronger binders. Repeat…until high affinity Add constant regions Examples: adalimumab (Humira) and belimumab .
139
# Definition
conserved nucleotide motifs upstream from gene segments that encode the constant regions of antibody heavy chains; the site of double-stranded breaks
Switch (S) region
140
Where does somatic hypermutation occur?
Germinal centres
141
An antigen can hae many tagets for a B-cell response, what is each of these targets referred to as?
Epitope
142
# Define
IgG
a type of antibody. Representing approximately 75% of serum antibodies in humans, it is the most common type of antibody found in blood circulation
143
# Definition
a type of T cell that play an important role in the immune system, particularly in the adaptive immune system. They help the activity of other immune cells by releasing T cell cytokines. These cells help suppress or regulate immune responses
CD4 T-cells
144
# Define
V(D)J recombination
the unique mechanism of genetic recombination that occurs only in developing lymphocytes during the early stages of T and B cell maturation. It involves somatic recombination, and results in the highly diverse repertoire of antibodies/immunoglobulins and T cell receptors (TCRs) found in B cells and T cells, respectively
145
What do the autoantibodies in Lupus target?
Molecules in the nuclei of cells (dsDNA, fibronucleoproteins, other nuclear proteins complexed with nucleic acids)
146
What is the issue with using monoclonal antibodies to treat Lupus?
None have shown broad, strong protection
All are expensive
147
# Define
Polyclonal response
a natural mode of immune response exhibited by the adaptive immune system of mammals. It ensures that a single antigen is recognized and attacked through its overlapping parts, called epitopes, by multiple clones of B cell
148
# Define
T regulatory cells
a specialized subpopulation of T cells that act to suppress immune response, thereby maintaining homeostasis and self-tolerance
149
# Definition
thin membrane that extends from skeletal tissue at interface of cartilage and bone and lines the capsule of synovial joints
Synovium
150
# Definition
sites within secondary lymphoid organs – lymph nodes and the spleen where mature B cells proliferate, differentiate, and mutate their antibody genes (through somatic hypermutation aimed at achieving higher affinity) during a normal immune response to an infection
Germinal centres
151
What 3 methods make the V region of every naive B-cell different?
1. A developmental mechanism that generates huge protein diversity from limited genetic diversity (V(D)J recombination mediated by RAG1&2)
2. After exposure to the antigen, additional diversification by so-called somatic hypermutation (SHM) mediated by the enzumes Activation Induced Cytidine Deaminase (AID)
3. Ig can be further diversified by changing the constant region (Class switch recombination also mediated by AID)
152
# Definition
the process by which daughter cells arise from a parent cell. When B-cells undergo this process, many copies of that B cell are produced that share affinity with and specificity of the same antigen
Clonal expansion
153
How do environmental triggers lead to Lupus?
Environmental trigger causes tissue damage and localised release of potential autoantigens (e.g. DNA spilling out of nucleus where it’s usually hidden from the immune system)
154
What happens to some strongly self-reactive CD4 T-cells?
They become regulatory T-cells
155
# Define
Receptor editing
secondary rounds of V-J gene segment rearrangement to generate a revised BCR that is no longer self-reactive
156
# Definition
proteins capable of recognizing molecules frequently found in pathogens (the so-called Pathogen-Associated Molecular Patterns—PAMPs), or molecules released by damaged cells (the Damage-Associated Molecular Patterns—DAMPs)
Pathogen recognition receptor (PRR)
157
What activates synovial macrophage-like cells in RA? What cytokines do they produce?
Immune complexes activate the cells
Which then produce TNF and IL-6 (and many others)
158
Why must all T-cell receptors show a degree of self-reactivity?
To avoid death by neglect
159
How do you isolate individual clones to have a pure antibody species?
Separate each different fusion so that each B cell clone now grows separately from all others (monoclonal culture and antibody production)
160
What are the four main methods of preventing autoantibody formation?
Deletion of self-reactive clones
B-cell receptor editing
Activation-induced cell death
T-cell dependence
161
How many times does somatic recombination occur in the heavy and light chains of a Ig molecule?
Light: 1, Heavy: 2
162
# Define
Germinal centres
sites within secondary lymphoid organs – lymph nodes and the spleen where mature B cells proliferate, differentiate, and mutate their antibody genes (through somatic hypermutation aimed at achieving higher affinity) during a normal immune response to an infection
163
# Define
Complementary determining regions (CDR)
part of the variable chains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively, where these molecules bind to their specific antigen
164
What are the treatment options for Lupus?
* Generalised immunosuppression
* Steroids (glucocorticoids): unacceptably severe side effects
* Monoclonal antibodies: poor record of success to date but anifrolumab showed impressive results in trials, when responses were analysed correctly
165
166
Why is an immunoglobulin molecule described as a dimer of dimers?
It has two identical heavy chains and two identical light chains
167
# Define
Plasmacytoid dendritic cell (pDC)
a rare type of immune cell that are known to secrete large quantities of type 1 interferon (IFNs) in response to a viral infection. They circulate in the blood and are found in peripheral lymphoid organs.
168
# Define
FcR
a antibody receptor involved in antigen recognition which is located at the membrane of certain immune cells including B lymphocytes, natural killer cells, macrophages, neutrophils, and mast cells. Such receptors recognize Fc fragment of antibodies
169
True or False:
Lupus occurs mostly in men
False
It occurs more in women 9:1
170
# Define
TH17 cells
by virtue of their production of IL-17 and IL-17F, are generally thought to be pro-inflammatory and play an important role in host defense against infection, by recruiting neutrophils and macrophages to infected tissues
171
# Definition
ectopic lymphoid organs that develop in non-lymphoid tissues at sites of chronic inflammation including tumours
Tertiary lymphoid sites
172
How do you make fully human mAbs from humans?
173
How does the pannus destroy cartilage and cone?
Cells within the pannus release factors that destroy articular cartilage and bone
174
# Define
IgA
an antibody that plays a crucial role in the immune function of mucous membranes
175
What five activities occur within germinal centres?
1. **Proliferation:** T cells drive clonal expansion of antigen-specific B cells
2. **Isotype switching:** Changing the constant region of the antibody heavy chain without changing the V regions and thus the specificity. Changes effector function of the Ab
3. **Somatic hypermutation:** Random introduction of point mutations into the V gene segments of the H and L chains to diversify binding to antigen.
4. **Affinity maturation:** Select those mutated B cells with improved affinity for antigen. Let the remainder die. Improves average affinity.
5. **Memory formation:** Induce high affinity GC B cells to differentiate into either memory B cells of plasma cells that leave the GC and live for long periods
176
Where is AID expressed?
AID is expressed only in activated B cells and thus in all Germinal Centre B cells
177
What happens to germinal centres after the immune response ends?
They disappear
178
How does the activation of the innate immune system contribyte to Lupus?
179
How does AID induce class switch recombination?
* The enzyme Activation Induced Cytidine Deaminase (AID) introduces nicks into S region DNA (contains ‘hot spots’ for AID activity, which converts C to U in DNA )
* AID is expressed only in activated B cells and thus in all Germinal Centre B cells
* Enough nicks are made to create double stranded (ds) breaks in two S regions
* Ends are joined, DNA is repaired, deleting the intervening chromosomal region.
* CSR is deletion recombination mediated by S-S recognition and requires double stranded breaks in the DNA that are generated by AID and repaired by nonhomologous end joining (NHEJ)
180
# Define
Hybridomas
A hybrid cell used as the basis for the production of antibodies in large amounts for diagnostic or therapeutic use. They are produced by injecting a specific antigen into a mouse, collecting an antibody-producing cell from the mouse's spleen, and fusing it with a tumor cell called a myeloma cell
181
Exons encoding Ig constant regions can’t be expressed until what?
Exons encoding Ig constant regions can’t be expressed until a V segment is placed upstream of them – true for all isotypes, H and L (stable, high level transcription).
182
How does the antibody response to an antigen switch from predominantly IgM to IgG during initial exposure?
Class switch recombination
183
What enzyme(s) mediate class switch recombination?
Activation Induced Cytidine Deaminase (AID)
184
When does B-cell tolerance occur?
After B-cell receptor (Ig) assembly and expression
185
# Define
Lymphocyte
white blood cells that are also one of the body's main types of immune cells. They are made in the bone marrow and found in the blood and lymph tissue
186
How are high affinity Ig/BCRs selected for following somatic hypermutation?
B-cells with higher affinity Ig compete bettwen for antigen and thus T-cell help
Since T-cells drive proliferation, high affinity B-cells contrinue to proliferate
Low affinity B-cells die in the GC
187
# Definition
an autoimmune disease that can cause joint pain and damage throughout your body
Rheumatoid arthritis
188
# Definition
an antibody that plays a crucial role in the immune function of mucous membranes
IgA
189
# Define
Avidity
the overall strength of binding between an antibody and an antigen
190
# Definition
the overall strength of binding between an antibody and an antigen
Avidity
191
# Definition
a specialized subpopulation of T cells that act to suppress immune response, thereby maintaining homeostasis and self-tolerance
T regulatory cells
192
True or False
Switch (S) regions are all homologous
True
193
In Rheumatoid arthritis, what is degraded by inflammatory processes?
Synovium
Bone tissue
194
What serotype is initially involved in a secondary exposure to an antigen?
IgG
195
# Definition
in a state or period of inactivity or dormancy
Quiescent
196
# Define
Isotype
the genetic variations or differences in the constant regions of the heavy and light chains
197
# Define
Pannus
an abnormal layer of fibrovascular tissue or granulation tissue. Common sites include over the cornea, over a joint surface (as seen in rheumatoid arthritis), or on a prosthetic heart valve
198
Autoantibodies are produced and can contribute to tissue damage in SLE. What happens when self-antigens continue to be produced?
Further release of self-antigens can stimulate innate activation and type I IFN production
199
# Define
Peripheral tolerance
the second branch of immunological tolerance, after central tolerance. It takes place in the immune periphery (after T and B cells egress from primary lymphoid organs). Its main purpose is to ensure that self-reactive T and B cells which escaped central tolerance do not cause autoimmune disease
200
Why are polyclonal antibodies a very useful therapeutic?
Useful because:
* Polyclonality covers a multitude of types for one protein (cross-reactivity)
* Easy, cheap, reliable
* Recognise multiple epitopes on one antigen
201
# Define
Deletion
the killing of self-reactive cells, appears to be the fate of high affinity anti-self. E.g. activation-induced cell death (AICD)
202
# Definition
causes mutations that produce antibody diversity, but that same mutation process leads to B cell lymphoma
Activation induced cytidine deaminase (AID)
203
What determines the shape of a binding site of a Ig molecules?
CDR genes
204
# Define
PAMPs
a diverse set of microbial molecules that share a number of different general “patterns,” or structures, that alert immune cells to destroy intruding pathogens
205
Ig isotypes are defined by the ________ part of the heavy chains
Ig isotypes are defined by the **constant** part of the heavy chains
206
# Define
Somatic hypermutation (SHM)
a cellular mechanism by which the immune system adapts to the new foreign elements that confront it (e.g. microbes), as seen during class switching
207
# Define
Rheumatoid arthritis
an autoimmune disease that can cause joint pain and damage throughout your body
208
# Definition
The portion of the amino acid sequence of an antibody's heavy or light chains that determines the class of the antibody and does not vary within a given class
Constant region
209
When does T-cell tolerance occur?
Tolerance occurs after T-cell receptor assembly and expression
210
Polymorphisms of genes in which areas tend to contribute to SLE?
Clearance of apoptotic particles and immune complexes
Innate immunity
Adaptive immunity
Tissue damage
211
212
Why can't you convert back into IgD after class switching to IgA?
The IgD gene has been deleted from that cell
213
Autoantibodies form immune complexes with what?
Autoantibodies form immune complexes with their autoantigen and complement proteins
214
Describe the cyclic exacerbation of Lupus
215
How do you make fully human mAbs in mice?
216
What are the 5 Ig isotypes?
IgG
IgA
IgM
IgD
IgE
217
# Define
Synovium
thin membrane that extends from skeletal tissue at interface of cartilage and bone and lines the capsule of synovial joints
218
What cells enable a plasma cell to survive by forming a niche?
Myeloid cells (DC, macrophages)
Basophils
Eosinophils
Magakaryocytes
Stromal cells
Neutrophils
219
Why can self-reactive cells be useful to protect against some foreign antigens?
Some pathogens mimic host cells in order to avoid the immune system
220
Why is there an issue with using glucocorticoids to treat Lupus?
Cost $$$
Side-effects (osteoporosis, diabetes, cataracts etc.)
221
Which of these immune processes are important in Rhumatoid arthritis and Lupus?
## Footnote
Lymphoid organogenesis
Antigen presentation and co-stimulation
Immune complexes
Autoantibodies
**Rheumatoid arthritis:**
Lymphoid organogenesis
Antigen presentation and co-stimulation
Immune complexes
**Lupus:**
Antigen presentation and co-stimulation
Immune complexes
222
Why is the bone marrow a good site for central tolerance?
There shouldn't be foreign antigens in the bone marrow so any strong BCR signalling inicates self-reactivity
223
# Definition
by virtue of their production of IL-17 and IL-17F, are generally thought to be pro-inflammatory and play an important role in host defense against infection, by recruiting neutrophils and macrophages to infected tissues
TH17 cells
224
# Definition
the second branch of immunological tolerance, after central tolerance. It takes place in the immune periphery (after T and B cells egress from primary lymphoid organs). Its main purpose is to ensure that self-reactive T and B cells which escaped central tolerance do not cause autoimmune disease
Peripheral tolerance
225
What determines different autoimmune phenotypes?
Self-reactivity in different cell types and pathways drives different autoimmune phenotypes
226
\_\_\_\_\_\_\_\_ signaling mediates the action of IL-6
**JAK-STAT** signaling mediates the action of IL-6
227
What type of stem cell do B-cells originate from?
Harmatopoiteic stem cells (HSC)
228
# Definition
a laboratory technique for the study of protein–protein, protein–peptide, and protein–DNA interactions that uses bacteriophages (viruses that infect bacteria) to connect proteins with the genetic information that encodes them
Phage display
229
After initial exposure to antigen, there is secretion of Ig\_\_ followed by Ig\_\_ or Ig\_\_
After initial exposure to antigen, there is secretion of Ig**M** followed by Ig**G** or Ig**A**
230
What happens to self-reactive B-cells?
They go through a round of receptor editing
231
Pairing of newly rearranged antigen receptor components results in a new antigen specificity that must be tested for what?
1. Signal transduction capacity
2. Reactivity against self
232
# Definition
a antibody receptor involved in antigen recognition which is located at the membrane of certain immune cells including B lymphocytes, natural killer cells, macrophages, neutrophils, and mast cells. Such receptors recognize Fc fragment of antibodies
FcR
233
How do JAK/STAT inhibitors treat RA?
Small molecule inhibition of Jak via competitive inhibition at the DNA binding site
Jak inhibitors interrupt many cytokine signalling pathways
234
True or False
Secondary response to antigen is usually not associated with CSR
True
235
# Definition
part of the variable chains in immunoglobulins (antibodies) and T cell receptors, generated by B-cells and T-cells respectively, where these molecules bind to their specific antigen
Complementary determining regions (CDR)
236
What enzyme creates a junction between two loci during somatic recombination (V(D)J recombination)?
RAG enzymes
237
# Define
Quiescent
in a state or period of inactivity or dormancy
