cytokine_questions_complete_final_v4 Flashcards
(223 cards)
1
Q
What are the six families of cytokines?
A
IL-1, Class I cytokines (hematopoietin), Class II cytokines (interferon), TNF family, IL-17 family, Chemokines
2
Q
What is the representative member of the IL-1 cytokine family?
A
IL-1α, IL-1β, IL-1Ra, IL-18, IL-33
3
Q
Name one cytokine from the Class I cytokine family (hematopoietin).
A
IL-2, IL-3, IL-4, IL-5
4
Q
Which cytokine family does Interferon (IFN) belong to?
A
Class II cytokines
5
Q
What are the representative members of the IL-17 family?
A
IL-17A, IL-17B, IL-17C, IL-17D, IL-17F
6
Q
What family do chemokines belong to?
A
Chemokines
7
Q
Which cytokine is a member of both IL-1 and TNF family?
A
IL-1β
8
Q
What is the role of IL-1 in cytokine signaling?
A
Initiates inflammatory response
9
Q
Name a cytokine involved in growth hormone signaling.
A
Insulin-like Growth Factor 1 (IGF-1)
10
Q
Which family of cytokines is associated with hematopoiesis?
A
Class I cytokines (hematopoietin)
11
Q
What function do TNF family cytokines have?
A
Involved in cell death and survival signaling
12
Q
Which family includes cytokines involved in the antiviral response?
A
Class II cytokines (interferon)
13
Q
Name a cytokine that is part of the chemokine family.
A
IL-8, CCL19, CCL21, RANTES
14
Q
What cytokine is part of the inflammatory response and also involved in fever production?
A
IL-1β
15
Q
Which cytokine is involved in the immune response and is a key player in autoimmune diseases?
A
IL-17
16
Q
What is the function of chemokines in immune cell trafficking?
A
Direct the movement of immune cells to sites of infection or inflammation
17
Q
Which cytokine is a major player in tumor necrosis?
A
TNF-α
18
Q
What is a key function of interferons (IFN)?
A
Inhibit viral replication and modulate the immune response
19
Q
What cytokine is critical in the adaptive immune response?
A
IL-2
20
Q
Which cytokine is important in the activation of macrophages?
A
IFN-γ
21
Q
Which cytokine family includes cytokines important for the differentiation of immune cells?
A
Class I cytokines (hematopoietin)
22
Q
Which cytokine promotes the survival of T cells?
A
IL-2
23
Q
Name a cytokine that stimulates the production of antibodies.
A
IL-4
24
Q
What role does IL-17 play in chronic inflammation?
A
Promotes the recruitment of neutrophils to sites of inflammation
25
Which cytokine family is known for regulating immune cell communication?
Chemokines
26
What cytokine is important in allergic responses?
IL-4
27
What is the key role of TNF-α in inflammation?
Induces the inflammatory response and regulates immune cells
28
What cytokine helps in the regulation of hematopoietic stem cells?
IL-3
29
Which cytokine is involved in both immunity and neural development?
IL-6
30
What are the main functions of cytokines in the IL-1 family?
Inducing primarily proinflammatory responses.
31
Name a cytokine from the Class I cytokine (hematopoietin) family.
IL-2, IL-4, IL-6, EPO (erythropoietin), GM-CSF
32
What is the primary function of Class I cytokines (hematopoietin)?
Regulation of hematopoiesis and immune function.
33
What receptor type do IL-1 family cytokines interact with?
Dimeric receptors.
34
What are interferons and which cytokine family do they belong to?
Interferons (IFN-α, IFN-β, IFN-γ) belong to the Class II cytokine family (interferon).
35
What is the role of Type I interferons (IFN-α and IFN-β)?
Mediating early antiviral responses.
36
What is the function of Type II interferons (like IFN-γ)?
Activating macrophages and supporting adaptive immunity.
37
Name a cytokine from the TNF family.
TNF-α, TNF-β, FasL, CD40L
38
How do TNF family cytokines typically interact with their receptors?
They act as trimers and can appear in soluble or membrane-bound forms.
39
What are the main functions of TNF family cytokines?
Inducing differentiation, survival, proliferation, and apoptosis.
40
What are the key characteristics of the IL-17 cytokine family?
Members are proinflammatory in action, promoting neutrophil recruitment and inflammation.
41
Name a member of the IL-17 family and its function.
IL-17A promotes the expression of proinflammatory cytokines and recruitment of neutrophils.
42
What is the primary function of chemokines?
Promoting the movement of immune cells into and out of lymphoid organs.
43
Name a chemokine and its target cell.
CCL19 attracts dendritic cells to lymph nodes.
44
Which chemokine attracts neutrophils to the site of infection?
CXCL8 (IL-8)
45
What is the structural feature used to classify chemokines?
The arrangement of cysteine (C) residues forming disulfide bonds.
46
What cytokine induces the expression of proinflammatory cytokines in neutrophils?
IL-17A
47
How does IFN-γ affect macrophages?
It activates them for enhanced immune response.
48
What is the role of erythropoietin (EPO) in the cytokine family?
EPO stimulates red blood cell production.
49
Which cytokine family is involved in cell death and immune signaling?
TNF family
50
What receptor does IL-1 bind to initiate its signaling pathway?
IL-1R1
51
What is the effect of TNF-α on apoptosis?
It promotes cell death (apoptosis) as part of immune regulation.
52
Which cytokine is crucial for the immune system's early response to viral infections?
IFN-α
53
How do Type III interferons (IFN-λ) function?
They are secreted by dendritic cells and play a role in antiviral defense.
54
What is the function of GM-CSF in the Class I cytokine family?
It stimulates the production and differentiation of white blood cells.
55
What is the role of IL-6 in the Class I cytokine family?
It is involved in immune response regulation and inflammation.
56
Which cells are primarily targeted by IL-17 family cytokines?
Neutrophils and other immune cells involved in inflammation.
57
How do chemokines like CCL19 and CXCL8 guide immune cells?
By attracting them to specific locations, such as infection sites or lymph nodes.
58
What is the first step in cytokine signaling?
Cytokine binding induces receptor dimerization.
59
What role do JAK kinases play in cytokine signaling?
JAK kinases phosphorylate each other and the receptor upon activation.
60
What happens after JAK kinases are activated?
They phosphorylate tyrosine residues on the receptor.
61
What is the role of STAT proteins in cytokine signaling?
STAT proteins bind to phosphorylated sites on the receptor.
62
How are STAT proteins activated?
STAT proteins are phosphorylated by JAK kinases.
63
What occurs after STAT proteins are phosphorylated?
Phosphorylated STAT proteins dimerize.
64
What is the final step in the JAK-STAT signaling pathway?
STAT dimers translocate to the nucleus to promote gene transcription.
65
What antimicrobial protein in the skin specifically targets E. coli?
Psoriasin
66
What is the function of RegIII protein in the intestine?
It prevents contact with epithelial cells and generates pores in the membrane.
67
What is the role of collectins (SP-A and SP-D) in the respiratory tract?
They block and modify surface components of encapsulated and non-encapsulated pathogens.
68
How do magainins in the skin attack pathogens?
They form pores by binding to acidic phospholipids in pathogen membranes.
69
What is the function of histatins in antimicrobial defense?
They interfere with mitochondrial ATP in fungi.
70
What is the function of defensins in the intestine?
They form pores by binding to acidic phospholipids in pathogen membranes.
71
What do Pattern Recognition Receptors (PRRs) recognize in pathogens?
Pathogen-associated molecular patterns (PAMPs).
72
Where are PRRs located in cells?
In the membrane (for extracellular pathogens), endosomes (for endocytosed pathogens), and the cytosol (for intracellular pathogens like bacteria and viruses).
73
What types of cells express PRRs?
Myeloid and lymphoid leukocytes, as well as epithelial cells exposed to infectious agents.
74
What structural feature characterizes Toll-like receptors (TLRs)?
Leucine-rich repeats (LRRs) that form a horseshoe shape.
75
How do Toll-like receptors (TLRs) dimerize upon ligand binding?
They form homodimers or heterodimers.
76
What types of pathogens do TLR2/1 and TLR4 recognize?
TLR2/1 recognizes gram-positive bacteria, while TLR4 recognizes gram-negative bacteria.
77
What signaling pathway is activated by membrane-bound Toll-like receptors (TLRs)?
Activation of AP-1 and NFκB.
78
What additional signaling pathway is activated by endosomal TLRs?
Activation of IRF (Interferon Regulatory Factor) in addition to AP-1 and NFκB.
79
What do C-type lectin receptors (CLRs) recognize?
Carbohydrate components of fungi, mycobacteria, viruses, parasites, and some allergens.
80
What immune response is triggered by C-type lectin receptors (CLRs)?
Generation of proinflammatory cytokines and activation of phagocytes.
81
What type of receptors are NOD-like receptors (NLRs)?
Cytosolic receptors.
82
What is the function of NOD1 and inflammasomes in the NLR family?
They generate antimicrobial proteins and peptides and activate autophagy to eliminate intracellular bacteria.
83
What is the specific function of the NLRP inflammasome?
It generates IL-1β and triggers pyroptosis through the formation of pores in the membrane.
84
What type of pathogens do NLRP inflammasomes respond to?
Intracellular pathogens such as bacteria and viruses.
85
What are the main effector mechanisms of the innate immune system after pathogen identification?
Antimicrobial peptides, cytokines, enzymes (iNOS, COX2), phagocytosis, autophagy, and cell death (NETosis, pyroptosis).
86
What antimicrobial peptides are produced by epithelial cells?
Defensins and cathelicidins.
87
What is the role of antimicrobial peptides in the immune response?
They inhibit and kill pathogens.
88
What cytokine is produced by infected cells to inhibit viral replication?
Interferon α/β.
89
What cells are activated by interferons in response to viral infections?
NK cells and macrophages.
90
What is the function of IL-1 in inflammation?
It regulates macrophage and lymphocyte activity and induces fever.
91
How does IL-6 influence the immune system?
It promotes neutrophil production in the bone marrow and enhances the acute phase response in the liver.
92
What is the effect of TNF-α on vascular endothelial cells?
It increases vascular permeability, leading to fluid loss and localized inflammation.
93
What process is activated by phagocytes to eliminate pathogens?
Phagocytosis.
94
How do lysosomes contribute to pathogen elimination during phagocytosis?
Lysosomes contain enzymes, antimicrobial proteins, and reactive oxygen and nitrogen species (ROS and RNS) to destroy pathogens.
95
What triggers inflammation during an innate immune response?
Tissue damage and the release of proinflammatory mediators like cytokines, which increase blood flow and recruit immune cells to the site of infection.
96
What are the four cardinal signs of acute inflammation?
Redness (erythema), heat, swelling, and pain.
97
What mutation is associated with Crohn's disease in the innate immune system?
Mutation in NOD2.
98
How does a NOD2 mutation contribute to Crohn's disease?
It reduces defensin secretion and alters the regulation of intestinal microbiota.
99
What is the consequence of altered intestinal microbiota in Crohn's disease?
It leads to increased Th1 and Th17 responses, producing proinflammatory cytokines like TNF-α and IL-17.
100
What role does regulatory T cell (Treg) deficiency play in Crohn's disease?
It exacerbates the proinflammatory response, contributing to disease progression.
101
What genetic mutations increase susceptibility to viral infections?
Mutations in signaling proteins that mediate the antiviral effects of IFN-α and IFN-β.
102
What is septic shock and what causes it in the immune system?
Septic shock is a life-threatening condition caused by an excessive immune response to infection, often triggered by LPS activating TLR4 and releasing TNF-α and IL-1β.
103
What are the consequences of septic shock on the body?
It causes vasodilation, low blood pressure, vascular damage, and can result in circulatory and respiratory failure.
104
How do regulatory mechanisms in the immune system prevent septic shock?
Endotoxin tolerance develops when macrophages are repeatedly exposed to LPS, leading to cytokine release followed by immune response inhibitors like IκB.
105
What is the role of IL-10 in immune regulation?
IL-10 is an anti-inflammatory cytokine that helps modulate immune responses and prevent excessive inflammation.
106
What is the function of pattern recognition receptors (PRRs) in immune regulation?
PRRs can work synergistically across different signaling pathways to enhance immune defense.
107
How do some pathogens evade detection by pattern recognition receptors (PRRs)?
By mutations such as those in proteobacteria flagellin, which prevent recognition by TLR5.
108
How do Helicobacter, Coxiella, and Legionella evade the immune system?
They alter their LPS so that it is not recognized by TLR4.
109
What is an example of a viral evasion mechanism targeting TLRs?
Viruses like Ebola and influenza produce proteins that block RIG-I signaling, preventing the activation of antiviral responses.
110
How does the Listeria bacterium evade immune destruction?
It escapes the phagosome into the cytosol to avoid lysosomal degradation.
111
What role do dendritic cells play in bridging the innate and adaptive immune systems?
Dendritic cells secrete cytokines that influence the differentiation of T cells based on the type of pathogen detected.
112
What cytokines are secreted by dendritic cells to promote Th1 differentiation?
IL-12 and IFN-γ.
113
What is the function of IL-10 and TGF-β produced by dendritic cells?
They promote the differentiation of regulatory T cells (Tregs), which help suppress excessive immune responses.
114
How do pathogens like Mycobacterium tuberculosis inhibit phagosome maturation?
They block fusion between phagosomes and lysosomes, preventing the acidification necessary for pathogen destruction.
115
What are the three pathways of complement activation?
The classical pathway, lectin pathway, and alternative pathway.
116
What is the key event where all complement activation pathways converge?
The cleavage of C3 into C3a and C3b.
117
What triggers the classical pathway of complement activation?
The binding of antigen-antibody complexes to C1q.
118
How is the lectin pathway activated?
By the binding of mannose-binding lectin (MBL) to microbial carbohydrates.
119
What activates the alternative pathway of complement?
Spontaneous hydrolysis of C3 on microbial surfaces.
120
What is the function of C3b in complement activation?
C3b opsonizes pathogens, marking them for phagocytosis, and contributes to the formation of the C5 convertase.
121
Which complement component initiates the formation of the membrane attack complex (MAC)?
C5b.
122
What role does C3a play in the immune response?
It acts as an anaphylatoxin, promoting inflammation by recruiting immune cells.
123
What is the convertase of C3 in the alternative pathway?
C3bBb + properdin.
124
What is the C3 convertase in the lectin and classical pathways?
C4b2b.
125
Which convertase is responsible for the cleavage of C5 in the alternative pathway?
C3bBb3b.
126
Which complement components form the membrane attack complex (MAC)?
C5b678 + polyC9.
127
In complement activation, what role does the C5 convertase play?
It cleaves C5 into C5a and C5b, initiating the formation of the MAC.
128
What initiates the lectin pathway of complement activation?
The binding of mannose-binding lectin (MBL) to microbial surfaces.
129
How does the classical pathway of complement activation begin?
With the binding of antibodies (Ig) to antigens, followed by C1 binding.
130
What is the lytic function of the immune system?
It refers to the destruction of cells or pathogens.
131
What does the antimicrobial function of the immune system do?
It fights against and eliminates microorganisms.
132
What role does the immune system play in proinflammatory responses?
It triggers inflammation as a response to infection or injury.
133
What is the chemotactic function in the immune system?
It involves guiding immune cells to the site of infection or damage.
134
How does the immune system function as an opsonizer?
It marks pathogens for destruction by phagocytes.
135
How does the immune system modulate acquired immunity?
It adjusts and enhances the adaptive immune response based on prior exposure to antigens.
136
What is the role of the immune system in the elimination of immune complexes?
It removes antigen-antibody complexes to prevent damage to tissues.
137
What is the homeostatic function of the immune system?
It maintains balance and stability in the body’s internal environment.
138
What protein blocks contact between epithelial cells and pathogens in the intestine?
RegIII
139
What proteins block and modify surface components of pathogens in the respiratory tract?
Collectins (SP-A and SP-D)
140
What is the function of magainins in the skin?
They bind to acidic phospholipids in pathogens and form pores.
141
What effect do histatins have on fungi?
They interfere with mitochondrial ATP in fungi.
142
How do PRRs differ based on their location?
PRRs are found in the membrane (for extracellular pathogens), endosomes/lysosomes (for endocytosed pathogens), and the cytosol (for intracellular bacteria or viruses).
143
What do Toll-like receptors (TLRs) recognize?
Leucine-rich repeats (LRRs).
144
What PRRs induce the activation of AP-1 and NFκB?
Membrane-bound PRRs.
145
What is the function of NOD receptors?
They generate antimicrobial proteins and peptides and activate autophagy to eliminate intracellular bacteria.
146
What does the NOD2 gene mutation cause in Crohn's disease?
A reduction in defensin secretion and alteration of the intestinal microbiota.
147
What is the main defect in innate immune susceptibility to viral diseases?
Mutation in proteins that interfere with the antiviral effects of IFN-α and IFN-β.
148
What activates TLRs during septic shock?
LPS activates TLR4, releasing TNF-α and IL-1β.
149
How do pathogens evade immune destruction?
Through mechanisms like avoiding detection by PRRs, blocking signaling pathways, and preventing inhibition of replication.
150
What is the common convergence point in complement pathways?
The C3 convertase.
151
What are the three pathways of complement activation?
Classical pathway, lectin pathway, and alternative pathway.
152
What are the main functions of complement?
Lytic, antimicrobial, proinflammatory, chemotactic, opsonizing, modulation of acquired immunity, elimination of immune complexes, and homeostatic.
153
What triggers the activation of the classical complement pathway?
Antigen-antibody complexes binding to C1q.
154
What role do C3a and C5a play in complement activation?
They induce inflammation and chemotaxis.
155
What induces immune complex elimination in the complement system?
C3b binding to CR1.
156
What pathogens alter complement signaling?
Viruses, bacteria, and fungi can block activation pathways or inhibit complement proteins.
157
Where are B lymphocytes generated?
In the bone marrow.
158
What is the primary function of B lymphocytes?
To produce antibodies.
159
What happens to B lymphocytes that are not activated in time?
They undergo apoptosis.
160
Why is B cell activation important?
It produces effector cells that secrete antibodies and memory cells for future infections.
161
What are antibodies and what is their function?
Antibodies are proteins that bind to antigens to facilitate their destruction.
162
What type of B cell activation is independent of the thymus?
Thymus-independent activation.
163
What type of antibodies are produced by B-1 lymphocytes during thymus-independent activation?
IgM and sometimes IgA.
164
What is the main difference between thymus-independent and thymus-dependent B cell activation?
Thymus-dependent activation involves T helper cells and produces a more specific and lasting response.
165
What processes occur in thymus-dependent activation of B-2 lymphocytes?
Somatic hypermutation and class switching of antibodies.
166
What antibodies are produced after thymus-dependent activation?
IgG or IgA.
167
What is the difference between plasma cells and memory B cells?
Plasma cells secrete antibodies, while memory B cells remain for future immune responses.
168
What is the basis of the effectiveness of vaccines?
The rapid response of memory B cells upon re-exposure to the same antigen.
169
What B lymphocytes are involved in innate humoral immunity?
B-1 lymphocytes.
170
How do B-2 lymphocytes interact with T helper cells?
Through complex immune synapses to activate a specific immune response.
171
What function does immune memory serve in the body?
It allows a faster and stronger response upon re-encounter with the same antigen.
172
What is the difference in antibody production between thymus-independent and thymus-dependent activation?
Thymus-independent activation produces antibodies with lower affinity, while thymus-dependent produces more refined and effective antibodies.
173
What is the antimicrobial protein in the skin that specifically targets E. coli?
Psoriasin
174
What protein prevents contact between epithelial cells and pathogens in the intestine?
RegIII
175
What proteins block and modify surface components of pathogens in the respiratory tract?
Collectins (SP-A and SP-D)
176
What function does magainin have in the skin?
It binds to acidic phospholipids of pathogens and forms pores.
177
What effect do histatins have on fungi?
They interfere with mitochondrial ATP production.
178
How do PRRs differ based on their location?
PRRs are located in the membrane (extracellular pathogens), endosomes/lysosomes (endocytosed pathogens), and cytosol (intracellular bacteria or viruses).
179
What do Toll-like receptors (TLRs) recognize?
Leucine-rich repeats (LRRs).
180
What PRRs induce the activation of AP-1 and NFκB?
Plasma membrane receptors.
181
What function do NOD-like receptors (NODs) have?
They generate antimicrobial proteins and peptides and activate autophagy to eliminate intracellular bacteria.
182
What causes the mutation in the NOD2 gene in Crohn's disease?
Reduction in defensin secretion and alteration of intestinal microbiota.
183
What is the primary defect in susceptibility to viral diseases related to the innate immune system?
Mutation in signaling proteins that mediate the antiviral effects of IFN-α and IFN-β.
184
What triggers TLR activation during septic shock?
LPS activates TLR4, releasing TNF-α and IL-1β.
185
How do pathogens avoid destruction by the immune system?
Through mechanisms like avoiding PRR detection, blocking signaling pathways, and preventing replication inhibition.
186
What is the common convergence point of complement activation pathways?
The C3 convertase.
187
What are the three pathways of complement activation?
Classical pathway, lectin pathway, and alternative pathway.
188
What are the main functions of complement?
Lytic, antimicrobial, proinflammatory, chemotactic, opsonizing, modulation of acquired immunity, immune complex elimination, and homeostatic functions.
189
What activates the classical complement pathway?
Antigen-antibody complexes binding to C1q.
190
What role do C3a and C5a play in complement activation?
They induce inflammation and chemotaxis.
191
What induces immune complex elimination in the complement system?
C3b binding to CR1.
192
What pathogens alter complement signaling?
Viruses, bacteria, and fungi can block signaling pathways or inhibit complement proteins.
193
Where are B lymphocytes generated?
In the bone marrow.
194
What is the primary function of B lymphocytes?
To produce antibodies.
195
What happens to B lymphocytes that do not activate in time?
They undergo apoptosis.
196
Why is B cell activation important?
It produces effector cells that secrete antibodies and memory cells for future immune responses.
197
What are antibodies and what is their function?
Antibodies are proteins that bind to antigens to facilitate their destruction.
198
What type of B cell activation is independent of the thymus?
Thymus-independent activation.
199
What antibodies are produced by B-1 lymphocytes in thymus-independent activation?
IgM and sometimes IgA.
200
What is the main difference between thymus-independent and thymus-dependent B cell activation?
Thymus-dependent activation involves T helper cells and produces a more specific and lasting immune response.
201
What processes occur in thymus-dependent B cell activation?
Somatic hypermutation and class switching.
202
What antibodies are produced after thymus-dependent activation?
IgG or IgA.
203
What is the difference between plasma cells and memory B cells?
Plasma cells secrete antibodies, while memory B cells persist for future immune responses.
204
What is the basis for the effectiveness of vaccines?
The rapid response of memory B cells when re-exposed to the same antigen.
205
What B lymphocytes are involved in innate humoral immunity?
B-1 lymphocytes.
206
How do B-2 lymphocytes interact with T helper cells?
Through complex immune synapses to activate a specific immune response.
207
What function does immune memory serve in the body?
It allows a faster and stronger response upon re-encounter with the same antigen.
208
What is the difference in antibody production between thymus-independent and thymus-dependent activation?
Thymus-independent activation produces antibodies with lower affinity, while thymus-dependent activation produces more refined and effective antibodies.
209
What is V(D)J recombination?
A process that combines V, D, and J segments to generate antibody and T-cell receptor diversity.
210
What are the three types of genetic segments involved in V(D)J recombination?
V (Variable), D (Diversity), and J (Joining) segments.
211
What function does V(D)J recombination serve in the immune system?
It generates antibody and T-cell receptor diversity to recognize multiple antigens.
212
What are the four main processes of V(D)J recombination?
Synapsis, cleavage, processing, and joining.
213
What happens during synapsis in V(D)J recombination?
The V, D, and J segments are selected and brought together.
214
What is the role of RAG1 and RAG2 proteins in V(D)J recombination?
They initiate recombination by recognizing recombination signal sequences (RSS).
215
What role does the enzyme TdT play in V(D)J recombination?
It adds random nucleotides to DNA breaks, introducing diversity.
216
What do DNA repair proteins like ligase IV and Artemis do in V(D)J recombination?
They repair and join DNA ends after cleavage.
217
What are recombination signal sequences (RSS)?
Sequences that indicate where DNA should be cut and joined during V(D)J recombination.
218
What function do endonucleases and exonucleases have in V(D)J recombination?
They cleave and modify DNA ends to allow effective recombination.
219
Where is the most variability generated during V(D)J recombination?
In the CDR3 region, where random nucleotides are added.
220
What proteins are responsible for ligating DNA ends after V(D)J recombination?
DNA ligase IV and XRCC4.
221
What do TdT and other enzymes introduce during recombination to increase diversity?
Random nucleotides.
222
What happens if DNA repair fails during V(D)J recombination?
It can lead to defects in antibody and T-cell receptor formation.
223
What is the final result of V(D)J recombination in terms of diversity?
A wide variety of antibodies and T-cell receptors that improve immune system responsiveness.
