Material Learned After Exam 3 Flashcards
1
Q
What are the 2 signals needed to trigger a B cell?
A
- Antigen BCR interaction
2. T cell cytokines
2
Q
How can the expression of MHC molecules be increased?
A
Via production of cytokines during
1. MHC I (aka innate immune response)
and
2. MHC II (aka adaptive immune response)
3
Q
How are T8-lymphocytes activated?
A
Epitope from endogenous antigenous are bound to MHC I molecules via/facilitated by dendritic cells
4
Q
T/F: All nucleated cells have MHC I molecules
A
True
5
Q
What allows T4 lymphocytes to recognize epitopes of exogenous antigens and discriminate self from non-self?
A
MHC II molecules
6
Q
What type of cell makes MHC II molecules?
A
Antigen presenting cells (APC)
7
Q
T/F: T cells, B cells, and natural killer (NK) cells are all the same.
A
False, NK cells are not the same as T and B cells
8
Q
What is the function of natural killer cells?
A
To destroy cancer cells & cells infected w/ intracellular pathogens
9
Q
Describe the mechanism used by natural killer cells.
A
- Cell is targeted if it lacks normal MHCs or specific proteins
- NK cell injects granzymes and perforins into the target cell which induce apoptosis within the target cell
10
Q
T/F: Natural killer cells need past exposure in order to recognize foreign cells
A
False
11
Q
T/F: Natural killer cells do not exhibit memory w/ target cells and are not enhanced.
A
True
12
Q
What are TH17 cells?
A
CD4+ T helper cells that produce the proinflammatory cytokine interleukin-17.
13
Q
What is the function of TH17 cells?
A
They protect host from fungal/bacterial infections at muscosal surfaces (ex. intestinal lining)
14
Q
What directly regulates the differentiation of TH17 cells in the intestine and why is this significant?
A
Regulated by: molecular circadian clock
Significance: suggests that nutrition and light are imp environmental factors that directly regulate the immune response
15
Q
These are glycoprotein molecules that interact specifically w/ antigenic determinants.
A
Antibodies/immunoglobulins (Ig)
16
Q
Name 2 functions of antibodies/immunoglobulins (Ig).
A
- act as antigen receptors of B cells
2. act as antibodies (soluble proteins) when secreted
17
Q
Name 3 substances that antibodies/immunoglobulins (Ig) can be found in.
A
- Serum
- Milk
- Gastric
18
Q
Describe the antigen binding sites.
A
Pockets located at the ends of fork-like structure of antibody
-contains a variable region thus resulting in a variety of antigen binding site shapes to fit a wide range of antigens
19
Q
What are the 5 major classes of antibodies/immunoglobulins (Ig)? What differentiates them? Which class is the most commonly found in the body?
A
- IgG<–most commonly found
- IgA
- IgM
- IgD
- IgE
- Differentiated from each other by their amino acid sequence
20
Q
Describe the structure of IgG.
A
- 4 poypeptide chains (2 heavy and 2 light chains)
- Interaction b/w light and heavy chains creates an antigen-binding site
21
Q
Where are each class of antibody/immunoglobulin found/involved in?
A
- IgM & IgG–>found in blood
- IgA–>found in secretions from mucous membranes (ex. spit, tears, breast milk)
- IgE–>involved in parasite immunity & allergies; functions as an antibody that binds to eosinophils
- IgD–>found on surface of B cell
22
Q
What are eosinophils?
A
White blood cells
23
Q
What is class switching?
A
Change in antibody class that’s secreted by plasma cells under the influence of helper T cells
24
Q
Describe the primary antibody response.
A
- Initial exposure to antigen
- Lag/latent period (several days-weeks); no antibodies detectable in blood
- B cell differentiation in plasma cells; antibodies are secreted
- IgM is secreted first and then IgG
25
What is an antibody titer?
A measure of serum antibody concentration
| -is the reciprocal of the highest dilution of antiserum that gives a positive reaction
26
What is the anamnestic response?
Renewed rapid production of antibodies on the second/subsequent encounter with the same antigen
27
What are the 5 actions that antibodies can perform when a foreign cell is detected?
1. Precipitation
2. Neutralization
3. Complement Fixation
4. Agglutination
5. Opsonization
28
Define: Precipitation
Soluble antigens (Ag) bind to soluble antibodies (Ab) to form immune complexes
29
Define: Neutralization
Antibody (Ab) binds to antigen (Ag), preventing the antigen from binding to the host cell
30
Define: Complement Fixation
Interaction between specific antitoxin antibodies and toxic antigens can prevent the toxic antigen from entering host cells
31
Define: Agglutination
Insoluble antigens (ex. viral or bacterial cells) are cross-linked together using antibodies
32
Define: Opsonization
Antibody binds to antigens on a larger molecule/cell, making it recognizable to a phagocytic cell (i.e. antigens will get eaten)
33
What are the 4 classes of immunity? How are each acquired?
1. Active Immunity
- via personal immune response to a microbe
2. Passive Immunity
- you receive preformed immunity made by another person (ex. mother->baby)
3. Natural Immunity
- via normal life experiences (not induced via medical means)
4. Artificial Immunity/Immunization
- produced purposefully through medical procedures
34
What is the difference between how natural passive and natural active immunity is acquired?
Passive: antibody transfer across the placenta or in breast milk
Active: acquisition of infection that initiates an adaptive immune response
35
Exposure to a controlled dose of a harmless antigen to induce formation of antibodies is called...
Artificial active immunity (vaccination)
36
Injection of an antiserum derived from an immune individual is called...
Artificial passive immunity
37
Immune serum globulin, specific immune globulin, and antisera/antitoxins of animal origin all fall under what class of immunization?
Passive Immunization
38
This immunization method is used to prevent measles, hepatitus A and in replacing antibodies in immunodeficient patients. It's injected intramuscularly and protection lasts 2-3 months. What is the name of this serum?
Immune serum globulin (ISG) (aka Gamma Globulin)
| -form of artificial passive immunity
39
This serum is obtained from a more defined group of donors, patients who are in a hyperimmune state after infections which means it contains higher titers of specific antibodies. What type of serum is this?
Specific immune globulin (SIG)
| -it contains a higher concentration of specific antibodies than ISG
40
T/F: Immunization with dead or inactivated material is just as effected as with live cells or a virus.
False. Immunization w/ live cells or a virus is more effective.
41
T/F: Most agents used for immunization are either inactivated pathogens or active forms of microbial products such as toxins.
False. Most are either attenuated/inactivated pathogens or inactivated forms of microbial products.
42
The process of generating an artificial active immune response by exposure to an antigen/antigen mixture is known as...
Immunization/vaccination
43
T/F: Vaccination involves exposing a person to material that is pathogenic but not antigenic.
False. Material is antigenic, not pathogenic.
44
T/F: For most pathogens, you only need to be immunized once in your life.
False, immunization usually involve a series of 2ndary or booster immunization to produce a 2ndary response and a higher antibody titer.
45
What is the purpose of vaccination?
To stimulate a primary and secondary anamnestic response to prime the immune system for future exposure to a virulent pathogen.
46
Define: Herd Immunity
Collective immunity through mass immunization confers indirect protection on non-immune members
-imp force in preventing epidemics
47
Why is it difficult to design vaccines for latent or persistent viral infections?
1. Host's natural immunity can't clear the infection
| 2. Artificial immunity must then outperform the host's response to a natural infection
48
Name 4 new strategies of administering immunization.
1. Synthetic peptides (ex. foot and mouth virus)
2. Recombinant-vector vaccines (ex. rabies vaccine)
3. Recombinant-antigen vaccines (ex. hepatitis B vaccine)
4. DNA vaccines (based on expression of cloned genes in host cells
49
Describe the Trojan horse vaccine.
1. Genetic material from an infectious agent is inserted into a live, nonpathogenic carrier microbe
2. Recombinant microbe multiplies and expresses the foreign gene
3. Vaccine recipient will be immunized against the microbial antigens
50
Structural components common to a particular group of infectious agents are known as...
Pathogen-associated molecular patterns (PAMPs)
| -includes polysaccharides, lipids, proteins, and nucleic acids
51
Soluble and membrane-bound host proteins that interact w/ PAMPs and promote phagocytosis are known as...
Pattern recognition receptors (PRRs)
| -found on the surface of macrophages, monocytes, neutrophils and dendritic cells
52
T/F: PRRs were first recognized in the fruit fly and were called Toll receptors.
True
53
Define: Toll-like receptors (TLRs)
Structural, function, and evolutionary homologs of the Toll receptors
-widely expressed on mammalian innate immune cells
54
Define: Nod-like receptors (NLRs)
Intracellular receptors of PAMPs that enter the cell via phagocytosis or through pores
55
What structural component of the cell acts as a barrier against PAMPs?
Cytoplasmic membrane
56
How does a cell respond to the danger w/out allowing the PAMPs into the cell?
Use signal transduction to initiate transcription & translation of host-response proteins, mainly those involved in phagocytosis and inflammation
57
What type of immunity are interferons involved in?
Innate immunity
58
Name the 3 major types of interferons (IFN) and each of their functions.
1. IFN alpha: stimulate phagocytes and activates NK cells
2. IFN beta: stimulate phagocytes, plays a role in inflammation, and mature T and B lymphocytes
3. IFN gamma: inhibits cancer cells, stimulates B lymphocytes, activates macrophages, and enhances phagocytosis
How: via binding to cell surfaces & inducing changes in genetic expression
59
T/F: Interferon classes are produced dependent on if the response is to viruses, RNA, immune products, or various antigens.
False. All 3 IFN classes are produced in response to viruses, RNA, immune products, and various antigens
60
What is the activation mechanism for phagocytes and lymphocytes in adaptive immunity?
Signal transduction
61
What structural component do adaptor molecules (that antigen receptors associate with) contain?
Immune-Based Tyrosine-Activation Motifs (ITAMs)
62
Define: Immunoglobulin gene superfamily
A large number of genes and their products that share structural, evolutionary, and functional features w/ immunoglobulin genes and proteins
63
Fill in the blank: Immunoglobulins (Ig, BCRs), T cell receptors (TCRs), and major histocompatibility complexes (MHCs) are all _____ proteins involved in the _____ immune response.
Antigen-binding/adaptive
64
T/F: Major histocompatibility complex (MHC) molecules have a low degree of polymorphism.
False. They have a high degree which explains their high diversity which may directly influence the survival of individuals against infectious disease
65
What is the human version of MHC?
HLC (human leukocyte antigen)
66
This is a major antigen barrier for tissue transplantation.
MHC proteins
67
Describe the steps that take place after a differentiated B cell is exposed to an antigen for the first time.
1. (B cell first acts like an antigen present cell) B cell binds to antigen through its surface antibody (BCR)
2. TH2 cytokine stimulation activates B cell which grows and differentiates into plasma cells that secrete antibodies targeted against the antigen
68
T/F: Each differentiated B cell is capable of producing BILLIONS of dif antigen-specific proteins each aimed to interact w/ one of the countless antigens in our environment.
True
69
Where are the variable domains of antibodies ESPECIALLY dif from one another?
Complementarity-determining regions (CDRs)
70
T/F: the antigen-binding site of an antibody is large enough to accommodate the binding of an epitope (10-15 amino acids long)
True
71
Ultimately, what is binding.
Binding=A function of the folding pattern of the heavy & light polypeptide chains
72
Name 4 ways that allow us to produce a near infinite diversity of antibodies.
1. Somatic recombination/combinatorial joining (mech. exclusive to T and B cells)
2. Random heavy and light chain reassortment
3. Coding for joint diversity (i.e. splice site variability)
4. Somatic hypermutation (B cells) of V regions after antigen exposure
73
Name 2 ways that somatic recombination could happen.
1. Rearrangement of antibody gene segments
| 2. Generation of different codons during antibody gene splicing.
74
What is the "Genes In Pieces" hypothesis?
Idea that the gene encoding each Ig is constructed from several Ig gene segments.
-during B-cell differentiation, exons for the constant region are joined to one segment of the variable region to produce a gene encoding a complete chain of an antibody
75
This process accounts for antibody receptors having higher antigen-binding strength during the 2nd exposure to antigen compared to the original B cell receptors.
Affinity maturation process
76
Compare and contrast the primary and secondary antibody response.
Primary: antigen-stimulated B cells multiply & differentiate to form antibody secreting plasma cells and memory cells--Secretes mostly IgM
Secondary: Previous memory B cells transform into antibody secreting cells--Secretes mostly IgG
77
T/F: T cell receptors (TCRs) bind to both self MHC and foreign peptides
True
78
T/F: TCRs and MHCs bind directly to peptide antigen
True
79
T/F: The CDR1 region of both alpha and beta chains bind to the epitope while as the CDR2 and CDR3 regions bind to the MHC protein
False. CDR3=binds to epitope. CDR1 and CDR2=bind to MHC protein
80
Name 3 genetic mechanisms that attribute to the diversity in T cell receptors (TCRs).
1. somatic recombination
2. random chain reassortment
3. coding for joint diversity
only occur on distinct gene segments on the alpha and beta chains
81
unresponsiveness/anergy to "self" is called...
Tolerance
82
How do T cells acquire tolerance?
Lymphocytes are maintained so that they interact only w/ the non-self antigens derived from dangerous pathogens
83
What happens to T cells that fail to develop tolerance?
Autoimmunity--inability to differentiate b/w self and non-self resulting in destruction in both
84
Describe the Clonal Selection Theory
- Each antigen-reactive B or T cell has a cell surface receptor for a single antigen epitope
- when stimulated, the cell replicates
- when selected, the clone expands
85
Elimination of clones of "self" antigens is known as...
Immune tolerance
86
Describe the positive and negative selection processes occurring in the thymus to determine which T cells have achieved tolerance.
Positive selection: T cells that interact w/ MHC peptide complexes are retained; T cells that don't interact w/ MHC-peptide stop growing and die
Negative selection: T cells that pass the positive selection but strongly bind w/ MHC-self peptides are selected against
After both selection processes, any surviving T cells leave the thymus and reenter the lymphatic circulation
87
T/F: More than 99% of T cells that enter the thymus pass the selection process.
False, more than 99% do NOT survive the selection process (i.e. clonal deletions occur)
