Quiz 1 Flashcards
What are the 5 types of infectious agents?
Bacteria
Viruses
Fungi
Parasites
Prions
What is the difference between a commensal organism and a symbiotic organism
a commensal organism benefits from close proximity to its host, while the host is unaffected (one-sided symbiosis)
Define immunogenicity
the ability of an organism to generate an immune response
What is colonization resistance?
the natural phenomena where microbiota inhibits colonization by newcomers
What are the most notable differences between eukaryotic cells and bacterial cells (prokaryotes)?
What is the main component of the bacterial cell wall?
peptidoglycan
What are two important cell wall polymers found in gram-positive bacteria?
What two peptides are commonly found in the peptidoglycan cell wall surrounding bacteria?
What are the four most notable components of the outer membrane of gram-negative bacteria?
What three elements compose the structure of lipopolysaccharide (LPS)?
Lipid A
Core oligosaccharide
O antigen
Which element of the structure of LPS is the endotoxin responsible for fever and shock?
Lipid A
Which element of the structure of LPS accounts for the virulence of gram-negative bacteria?
O antigen
What are examples of three genus of gram-positive cocci/diplococci?
Staphylococcus
Streptococcus
Enterococcus
What are examples of three genus of gram-positive bacilli/rods?
Bacillus
Clostridium
Listeria
What is an example of a gram-positive pleomorphic rod?
Corynebacterium
What are three examples of gram-negative cocci/diplococci, or coccobacilli?
Neisseria
Moraxella
Hemophilus
What are three examples of gram-negative bacilli/rods?
E- coli
Klebsiella
Psuedomonas
What are three examples of gram-negative curved/spiral rods?
Vibro
Campylobacter
Helicobacter
Why do ureaplasma and mycoplasma not gram stain? What is the clinical significance?
they lack a cell wall
they are insenstivie to beta-lactam antibiotics
Mycobacteria can stain gram-positive weakly; what are two notable molecules found in their cell wall?
mycolic acids
lipoarabinomannan (LAM) (a glycolipid)
What three antigens serve as the basis for serotyping pathogens?
O antigen (LPS)
K antigen (capsule)
H antigen (flagellin)
What is the maximum net yield of ATP in bacteria performing aerobic respiration?
36-38 ATP
What is the maximum net yield of ATP in bacteria performing anaerobic respiration?
2-36 ATP (can use non-oxygen final electron acceptor)
What is the maximum net yield of ATP in bacteria performing fermentation?
2 ATP
How is a bacteria that requires oxygen for metabolism classified?
Obligate aerobe
How is a bacteria that can grow with or without oxygen for metabolism classified?
Facultative anaerobe
How is a bacteria that can survive with only very little oxygen for metabolism classified?
Microaerophilic bacteria
How is a bacteria that is poisoned by oxygen classified?
Obligate anaerobe
What three enzymes can play a role in detoxification in aerobic or facultative bacteria?
superoxide dismutase
catalase
peroxidase
What is the difference in thickness of the peptidoglycan layer in gram-positive vs gram-negative bacteria?
gram-positive- 20-80nm
gram-negative- 5-10nm
Which bacteria are catalase positive?
Staphylococci
Pseudomonas aeruginosa
Enteric bacteria
Mycobacterium tuberculosis (at low body T)
What are protein secretion systems?
Which protein secretion system type is known as an injectosome or needle-like protein, and is commonly found in Yersinia, Psuedomonas, Salmonella, Shigella, and E. coli?
Type III secretion system
What is the major determinant of virulence in virulent strains of bacteria?
Exotoxins
T/F: Secretion is the exclusive method of trasmitting exotoxins for bacterial cells
F: Exotoxins can also be released by lysis of the bacterial cell in some cases
T/F: Endotoxins are cell-associated substances that are structural components of the peptidoglycan layer of bacterial cells
F: Endotoxins are structural components of the outer membrane (LPS) of gram-negative bacteria
Many (not all) bacterial exotoxins have an A-B structure for their components. What are the functions of each subsection?
B- binding component that triggers uptake
A- active component that has enzymatic activity
Though there are other types of exotoxins, what are the four major types of exotoxins taught in H&D? Give a short description of each type
Enterotoxins- act in GI to cause increased fluid secretion
Neurotoxins- act on nerves to cause paralysis
Pyrogenic exotoxins- stimulate cytokine release (rash, fever, TSS)
Tissue invasive exotoxins- allow bacterial to circumvent cell/tissue barriers
How does a superantigen present itself to T cells? What characterizes the reaction after binding?
How are endotoxins secreted from a bacteria into the host during an infection?
via cell lysis or detachment (not actively secreted)
Are either exotoxins or endotoxins heat stable?
Which part of the LPS structure is most responsible for endotoxin release?
Lipid A
What important virulence factor is associated with H antigen?
flagella
Bacterial adhesin proteins are most often associated with hair-like fibers called what?
pili or fimbriae
Some gram-positive bacteria can form spores. What are three notable facts about spore formation?
spores form during a nutrient shortage
spores lack metabolic activity
spores contain dipicolonic acid (granting heat resistance)
Will most antibiotics and hand sanitizers kill spores?
No
Does the replication fork in bacterial DNA replication proceed in one or two directions?
two directions
By what four processes does bacterial gene exchange occur?
Transformation
Conjugation
Transduction
Transposition
What are the three types of bacterial horizontal gene transfer (HGT)?
What is meant by labeling a bacteria as “competent”
It is able to take up DNA
During bacterial conjugation, the donor cell with the pilus is referred to as F+ or F-?
F+
What are transposable elements in bacterial DNA?
DNA elements that can jump from one place in bacterial DNA to another, transferring genes or disrupting genes when they insert
What is the main advantage that capsules give to encapsulated bacteria?
Protection from opsonization/phagocytosis
Which 5 notable encapsulated bacteria are opsonized and cleared by the spleen?
Streptococcus pneumoniae
Hemophilus influenzae
Escherichia coli
Neisseria meningitidis
Salmonella typhi
Peptidoglycan is especially suceptible to what enzyme created by the human body?
lysozyme
Bacterial flagella depend on what substrate instead of ATP?
protons
What is the general function of quinolone medications?
inhibition of unwinding of DNA by DNA gyrase during DNA replication
What virulence factor is presented in the capsule of encapsulated bacteria?
K antigen
What important diseases/infections are associated with Streptococcus pneumoniae?
Bacterial meningitis
Otitis media
Pneumonia
Sinusitis
What important diseases/infections are associated with Streptococcus agalactiae?
Bacterial meningitis
What important diseases/infections are associated with Staphylococcus aureus?
Pneumonia
Eye infections
Skin infections
Food poisoning
What important diseases/infections are associated with Streptococcus pyogenes?
Skin infections
Upper respiratory tract infections
What important diseases/infections are associated with Psuedomonas aeruginosa?
Skin infections
UTI
What important diseases/infections are associated with Escherichia Coli?
Food poisoning
UTI
What important diseases/infections are associated with Staphylococcus saprophyticus?
UTI
When possible, should bacterial samples be collected before or after administration of microbial agents?
before
When would electron miscroscopy be used in direct visualization of bacteria?
In order to view bacterial structures
What is the main difference between the Ziehl-Neelson acid-fast staining method, and the Kinyoun acid-fast staining method?
Ziehl-Neelson: specimen is heated during staining
Kinyoun: cold acid-fast
What is the color visualized for both acid-fast positive and acid-fast negative bacteria?
Acid-fast positive is RED
Acid-fast negative is BLUE
*counterstain is methylene blue
Which types of bacteria undergo alpha hemolysis when plated on a blood agar?
Streptococcus pneumoniae
Viridians group Streptococci
What types of bacteria undergo beta hemolysis when plated on a blood agar?
Streptoccocus pyogenes
Streptococcus agalactiae
Staphylococcus aureus
Psuedomonas aeruginosa
What notable bacteria undergoes gamma hemolysis (no hemolysis) when plated on a blood agar?
Enterococcus faecalis
What two fastidious organisms are selective for chocolate agar?
Haemophilus influenzae
Neisseria species
What is a Colistin and Nalidixic acid (CNA) agar selective for?
Gram-positive bacteria
What does a MacConkey agar select for? What additional differentiation can it provide?
Gram-negative bacteria
It can differentiate lactose fermenters vs. non-lactose fermenters
What color will lactose fermenters turn on a MacConkey agar?
pink
What four notable bacteria are lactose fermenters? (CEEK)
Citrobacter
Enterobacter
E. coli
Klebsiella
What is the Thayer-Martin media selective for?
Neisseria sp.
What is the presentation of a positive catalase test in the lab?
Visible O2 bubbles
A rapid agglutination test can be used to identify what type of bacterial infection?
Group A streptococcus
The complement system consists of proteases in ________ form?
inactive
What are the three anti-microbial functions of complement?
Direct destruction of pathogen
Opsonization
Inflammatory response
What are the three pathways of complement activation?
What characterizes the Alternative pathway of complement activation?
-Activated by exposure to pathogen membranes
-First pathway to act- immediate
What characterizes the Lectin pathway of complement activation?
-Activated by mannose-binding lectin (MBL)
-MBL produced by liver during systemic inflammation (24-48 hours post infection)
What characerizes the Classical pathway of complement activation?
-Activated by antibodies
-5-7 days after 1st exposure
-immediately after second exposure
What are the three main effector functions of the C3 convertase?
What are the main effector functions of the C5 convertase?
How do phagocytes (macrophages, neutrophils and eosinophils) detect opsonized targets?
What are the three main actions of C3a and C5a in promoting inflammation?
- Activation of endothelial cells to induce vasodilation and migration of leukocytes into tissue
- Increased activation of leukocytes, including mast cell and basophil degranulation
- Acting as chemotactic factors
How is the C3 convertase formed in the classical pathway?
Components of C1 cleave C2 and C4 to induce the formation of the C3 convertase (C4bC2b)
How is the C3 convertase formed in the lectin pathway?
MASP proteases cleave C2 and C4 to induce the formation of the C3 convertase (C4bC2b)
How is the C3 convertase formed in the alternative pathway?
Factor D cleaves C3 into C3a and C3b
C3b binds to bacterial surface
Factor D cleaves Factor B to form Bb fragment
C3b and Bb form C3 convertase (C3bBb)
How does C1 INH regulate activation of complement?
It is a regulator of C1 in the classical pathway
How do Factors H and I, as well as DAF and MCP regulate activation of complement?
They destabilize the C3 convertase in the alternative pathway
How does CD59 regulate the activation of complement?
It destabilizies the membrane attack complex (MAC)
What occurs when the pattern recognition receptors (PRRs) on a macrophage or dendritic cell bind a pathogen?
What are 5 principle examples of pattern-associated molecular patterns (PAMPs)?
- LPS
- Peptidoglycan
- flagellin
- Viral dsRNA, ssRNA
- Lipoproteins/fungal sugars
What are toll-like receptors (TLRs)?
A type of PRR used by immune cells to bind PAMPs
LPS, a major PAMP, is recognized by what receptor/receptor combination?
TLR4 paired with CD14
What is the immediate effect of a PAMP binding a TLR?
activation of NFkB and cytokine production
What are the 3 most important cytokines in the immune response (for H&D)?
IL1, IL6, and TNF
What is the acute phase response?
The production of serum proteins by the liver during systemic inflammation?
What are the three major effects of the acute phase response?
What are two common tests used for systemic inflammation?
C- reactive protein (CRP)
Erthryocyte sedimentation rate (ESR)
How does IL1 induce fever during systemic inflammation?
IL1 -> hypothalamus -> increase COX1, COX2 -> arachidonic acid -> prostaglandins -> fever
What cytokine is most associated with septic shock? What is pathology for septic shock?
TNF
systemic vasodilation, edema, and loss of organ perfusion leading to organ failure
What is the principle anti-viral cytokine?
IFNa/B
What does IFN-alpha or IFN-beta activate?
Natural killer cells
NK cells are an early source of what interferon?
Interferon gamma
What molecules are expressed upon endothelial cell activation?
Chemokines (IL8)
Adhesion molecules (selectins and ICAMs)
What molecule induces neutrophils to stop rolling and firmly adhere to endothelial cells?
LFA-1, a high-affinity integrin
Can migration to inflamed tissues occur without chemokines?
No
Can any inflammatory response be achieved without chemokines?
No
Can any adaptive immune response occur without chemokines?
No
What are the four hallmarks of inflammation?
Rubor (redness)
Tumor (swelling)
Calor (heat)
Dolor (dolor)
What 4 molecules principally activate local capillary endothelium?
IL1, TNF, C3a and C5a
Which leukocytes are involved in phagocytosis of foreign particles?
Which leukocytes are involved in degranulation?
Which leukocytes are involved in extracellular DNA traps?
Which leukocytes are involved in direct cytotoxicity?
Which leukocytes are involved in direct cytotoxicity?
What are the 5 deadliest features of the phagolysosome?
- Acidification
- Oxidative burst (NADPH oxidase)
- Nitrosative burst (NO synthase)
- Enzymatic degradation (lysozyme, myeloperoxidase, proteases, lipases, etc)
- Defensins and other anti-microbials
Phagolysosome function is enhanced in the presence of what interferon?
interferon gamma
What three enzymes do bacteria often employ to counterbalance the effects of an oxidative burst?
Superoxide dismutase
catalase
peroxidase
Granules secreted by NK cells contain what two notable molecules?
Perforin
Granzyme B
Deficiences in complement are most closely associated with suceptibility to what kind of infection?
Neisseria meningitidis infection
How does ia Factor H/I deficiency lead to an increased suceptibility to Neisseria meningitidis infection?
Loss of negative regulation of complement leads to constant over-activation and over-consumption of C3
Deficiencies in C1, C2, C4 or MAC lead to increased suceptibility to what kind of infection?
Neisseria mengitidis infection
What are two notable syndromes associated with complement deficiency?
Paroxysmal noctural hemoglobinuria (PNH)
Hereditary angioedma (HAE)
What are the clinical presentations of hereditary angioedema?
Rapid swelling of hands, feet, limbs, face, and GI tract due to overproduction of bradykinin, caused by loss of or misfunction of C1 INH
What characterizes Chronic granulomatous disease?
defective NADPH oxidase
What characterizes Chediak-Higashi syndrome?
Mutations in CHS1 (LYST) gene impairing trafficking of granules and vesicles, including failure to form functional phagolysosomes
What characterizes Leukocyte adhesion deficiency?
Loss of LFA-1
How does SARS CoV-2 inhibit the innate immune system?
Inhibition of cytoplasmic pattern recognition
Inhibition of NFkB or IRFs
Inhibition of production of IFNa/B
Interruption of cytokine signaling
Where does central tolerance occur in the body? What two processes occur to promote central tolerance?
Where does peripheral tolerance occur in the body?
Circulating T cells
An activated DC (+ signal 2) has what effect on circulating T cells as a function of peripheral tolerance?
An inactivated DC (no signal 2) has what effect on circulating T cells as a function of peripheral tolerance?
What two roles do Treg cells play in peripheral tolerance?
Convert activated DCs into regulatory DCs
Secrete immunosuppressive cytokines IL-10, and TGF-beta
Treg cells are regulated by what transcription factor?
FoxP3
What condition results from FoxP3 mutations?
Immunodysregulation polyendocrinopathy enteropathy X-linked syndrome (IPEX)
Why is a complete loss of function in FoxP3 likely not observed?
It would leadto overwhelming autoimmunity resulting in death
Which two types of hypersensivity reactions are mediated by IgG?
Type II (cell-associated antigens)
Type III (antigen immune complexes)
Which type of hypersensitivity reactions are mediated by IgE?
Type I (allergic reactions)
Which type of hypersensitivity reaction is mediated by T cells?
Type IV
What are the three major reasons that tolerance mechanisms break down?
Genetics
Environmental factors
Infectious history
What elements of genetics can contribute to breakdown of tolerance mechanisms?
HLA mutations (most important)
Sex
Immunoregulatory genes
What environmental factors can contribute to breakdown of tolerance mechanisms?
Smoking, weight, age, diet, etc
What elements of infectious history can contribute to breakdown of tolerance mechanisms?
similarity between foreign and self antigens (i.e. molecular mimicry)
What is the signifiance of the HLA-B27 allele in context of hypersensitivity reactions?
Its association with:
psoriasis
ankylosing spondylitis
IBD
reactive arthritis
Are males or females more suceptible to hypersensitivity reactions (especially in 3rd, 4th, and 5th decade of life)?
Females
To what two types of antigens can hypersensitivty reactions be directed?
Foreign antigens
Self antigens
What is the general role of Tregs?
To suppress harmful immune responses through direct supression of APCs and secretion of immunosuppressive cytokines (IL-10 and TGF-beta)
Do autoimmune diseases tend to be single gene dysfunctions or results of complex genetic and environmental factors?
Complex genetic and environmental factors, though single gene dysfunctions also occur
What is the target of aminoglycosides in bacterial cells?
the 70S ribosomal subunit
What is the action of quinolone antibiotics on the bacterial cell?
They inhibit the unwinding of DNA by DNA gyrase
What element of the immune response is found to be highly enriched in mucus?
defensins
Of the major inflammatory cytokines (IL1, IL6, and TNF) which is responsible for triggering the acute phase reaction?
IL6
Of the major inflammatory cytokines (IL1, IL6, and TNF) which is responsible for triggering septic shock?
TNF
Of the major inflammatory cytokines (IL1, IL6, and TNF) which is most responsible for triggering fever?
IL1
Of the major inflammatory cytokines (IL1, IL6, and TNF) which are responsible for phagocyte activation?
IL1, IL6, and TNF
Of the major inflammatory cytokines (IL1, IL6, and TNF) which is responsible for activating endothelial cells?
IL1 and TNF
Is increased hematopoeisis a result of the local or systemic immunologic response?
Systemic effects (GM-CSF, G-CSF)
What are the main results of the acute phase response?
Increased in complement factors C3, Factor B, C9, etc
Increased pathogen recognition (MB-Lectin, C-reactive protein)
Increased coagulation
What types of pathogens are Type I interferons (IFN a, IFN b) specific for?
Viral pathogens
What is the main function of IFNa/B?
activating natural killer cells
What major function do NK cells utilize in addition to directly killing virally infected cells?
Acting as an early source of IFN gamma
What is the immediate result of endothelial cell activation (by C3a, C5a)?
expression of adhesion molecules (ICAMs, selectins, addressins)
vasodilation
What effect does interferon gamma have on phagolysosome function?
It enhances it
Secretory granules used by NK cells to kill infected targets contain what 2 notable molecules?
Perforin
Granzyme B
What disease is characterized by an inability to make glycosylphosphatidylinositol (GPI) anchors, leading to intravascular hemolytic anemia and thrombosis?
PNH
What are four parameters in the definition of systemic inflammatory response syndrome (SIRS)?
Temperature
Heart Rate
Respiratory Rate
WBC count
What is the main difference between molecule binding in B cells and T cells?
B cells can bind soluble, free-floating antignes (almost anything)
T cells can only bind small, peptide antigens presented by MHC
How small are the peptide antigens that MHC can present to T cells?
8-20 AA long peptides
CD8+ T cells are activated by which MHC class?
CD4+ T cells are activated by which MHC class?
What are the three MHC class I genes?
HLA-A
HLA-B
HLA-C
What are the three MHC class II genes?
HLA-DP
HLA-DQ
HLA-DR
All nucleated cells express which MHC class?
MHC class I
Professional antigen presenting cells (macrophages, DCs, B cells) express which MHC class?
MHC class II
Which subunits comprise the structure of the MHC class I molecule?
Which subunits comprise the structure of the MHC class II molecule?
Which subunits comprise the structure of the MHC class II molecule?
Which genes are the most polymorphic in the human genome, with over 15,000 polymorphic variants?
MHC genes (HLA locus)
Cytosolic antigens (often from viruses) are more likely to be presented by which MHC class?
MHC class I
How are antigens attached to the MHC class I receptor? How does the receptor end up on the cell surface?
What is significant about the binding of CLIP to MHC class II molecule? Why is binding of HLA-DM to MHC class II significant?
CLIP prevents binding of peptides to MHC
HLA-DM binding to MHC class II releases CLIP, allowing peptides to bind and MHC class II molecule to travel to the surface
What is cross-presentation? What cell holds this function?
What is the purpose of the variable region of an antibody?
antigen recognition
What is the purpose of the constant (Fc) region of an antibody?
Effector functions like complement activation and opsonization
How many unique antigens receptors are expressed by a naive or resting B cell?
1
Which antibody is associated with mast cell/eosinophil activation?
Which antibody is not secreted, but is expressed on surface of naive B cells along with IgM?
Which antibody is the earliest produced, can activate complement, and participate in neutralization of pathogens?
Which antibody can activate complement, particpate in neutralization of pathogens, opsonization, ADCC, and is the most prevalent in serum?
Which antibody can participate in neutralization reactions and is associated with mucosal surfaces?
T/F: Antibodies are limited to binding protein structures only
False
The B cell receptor is associated with adaptor molecules that use what intracellular signals?
Ig-alpha and Ig-beta
The T cell receptor is associated with adaptor moelcules that use what intracellular signals?
CD3 (multiple subunits)
What is the signifiance of IL-7? What is the result of deficient IL7 signaling?
IL7 is important for lymphoid commitment
What is the role of RAG recombinase in DNA recombination?
What is the role of TdT during DNA recombination?
How many heavy and light chain loci exist for antibodies?
2 light chain loci (4 alleles)
1 heavy chain loci (2 alleles)
X-linked agammaglobulinemia is a defect in what kinase?
Bruton’s Tyrosine Kinase
What is the role of Bruton’s Tyrosine Kinase (Btk)?
To signal that productive antigen receptor is present at the cell surface of pre-B cells
What effect does a Btk deficiency have on positive selection for B cells?
Positive selection fails due to lack of signaling -> apoptosis
What are part 1 and part 2 of positive selection for T cells? Where do these processes occur?
1- Productive TCR rearrangement/expression
2- Recognition of host MHC by TCRs
the cortex of the Thymus
Where does negative selection occur for T cells?
The medulla of the thymus
What rough percentage of thymocytes die due to a failure to recognize self MHC (positive selection part 2)?
95-99%
What important ligand is associated with High endothelial venules (HEVs)?
L-selectin
Traffick to T cell and B cell zones is driven by what kind of molecules?
cytokines
What is Common Variable Immunodeficiency (CVID)?
A group of variable defects in antibody response; loss of one, some , or all isotypes
What is the most common subtype of CVID? What are common signs/sx? What are two increased disease risks for CVID patients?
In addition to PRR-induced activation, what cytokines are used to activate DCs during an infection?
Given the following diagram, a deficiency in LFA-1 or ICAM-1 could have what effect on the immune system?
Impaired activation of naive T cells by dendritic cells
Also, could effect the ability of neutrophils to transmigrate through capillaries to site of infection
What 3 signals are needed for T cell activation?
- TCR signaling
- Costimulation
- Cytokine-induced effector differentiation
What composes the TCR signaling (signal 1) component during T cell activation?
TCR + pMHC +co-receptor (CD4 or CD8) + CD3
What composes the costimulation (signal 2) component during T cell activation?
B7:CD28
B7.1 = CD80
B7.2 = CD86
What are the two negative costimulatory signals that are expressed after T cell activation?
CTLA-4
PD-1
How does CTLA-4 compete with CD28 to bind to B7?
It binds with higher affinity; competitive inhibition
What constitutes the cytokine component (signal 3) of T cell activation?
Various (IL-12 is notable), which can be supplied by antigen-presenting cells (APCs) and other cell types
What is significant to know about TCR signaling?
1: Activation of TKs (ZAP-70)
2: Ca2+ dependent activation of NFAT
TK-dependent activation of NFkB & AP-1
What are the overall roles of NFAT, NFkB, and AP-1?
What is the most specific significant action in T cell clonal expansion triggered by NFAT, NFkB, and AP-1?
What signal 3 cytokine induces Th1 cell differentiation? What cytokines does Th1 preferentially release?
What signal 3 cytokine induces Th2 cell differentiation? What cytokines does Th2 preferentially release?
What signal 3 cytokine induces Th17 cell differentiation? What cytokines does Th17 preferentially release?
What signal 3 cytokine induces Treg cell differentiation? What cytokines does Treg preferentially release?
What effector functions are the most important for Th1 cells?
Enhancing the microbial activity of macrophages
(CD40/CD40L pathway)
What effector functions are the most important for Th2 cells?
IL4, IL13 pathway: Alternatively activated macrophages (M2)
IL5 pathway: Activation of eosinophils and mast cells
What effector functions are most important for Th17 cells?
IL17: Increased neuotrphils
IL 22: Increased mucosa-associated defenses
What effector functions are most important for Treg cells? When do the chiefly arise?
Mostly IL10, TGF-beta mediated immune suppression
They mainly arise
1) during thymic selection
2) during T cell responses to foreign pathogens
What type of T cell is responsible for helping to enhance B cell activation?
T follicular helper cells (Tfh)
By what mechanisms do Tfh cells enhance B cell activation?
What two critical processes in the germinal center are initiated by Activation-induced deaminase (AID)?
What is the main benefit of isotype class switching in B cells?
The ability to switch to producing a specific antibody type more relevant to the pathogen/antigen exposure
What is the end goal of somatic hypermutation?
To produce a higher level of antigen binding specificity/affinity
What is Affinity maturation?
Multiple rounds of somatic hypermutation with the goal of producing higher level of antigen binding specificity/affinity
What specific cell type is especially important to enhance the process of affinity maturation?
Can the germinal center occur without Tfh cell migration into the B cell follicle?
No
Which antibody types can participate in neutralization of pathogens?
Which antibody types can participate in opsonization of pathogens?
Which antibody types can participate in complement activation?
Which antibody types can participate in mast cell activation?
What is the primary site of VDJ recombination in developing B cells?
the lymph node
Which antibody types can participate in antibody-dependent cell-mediated cytotoxicity (ADCC)?
Which antibody isotype can most readily cross the placenta?
IgG
Which viruses are double-stranded DNA viruses?
Herpes viruses
Which MHC allele is notable for a link between its mutation and psoriasis, anklyosing spondylitis, IBD, and reactive arthritis?
HLA-B27
Which immunosuppressive cytokines are principly secreted by Tregs?
IL-10 and TGF beta
Which type of cell drives T1 hypersensitivty reactions?
Th2 cells
The first exposure (sensitization) of a T1 hypersensitivity reaction involves what two actions by Th2 cells?
What occurs during second exposure of a T1 hypersensitivity reactions?
Mast cell degranulation triggered by antigens binding IgE
What molecule is responsible for vasodilation and bronchoconstriction in the early phase allergic reactions (within minutes)
What two types of molecules are responsible for local and systemic reactions as part of the late phase allergic reaction (8+ hours)?
Cytokines (IL4, IL5, TNF)
Leukotrienes
The early phase of an allergic reaction is driven by what molecule? What are common symptoms?
Histamine (induces vasodilation)
Urticaria, edema, rhinintis, asthma
The late phase of an allergic reaction is driven by what molecules?
Leukotrienes and cytokines
What are the go-to treatments for allergic reactions (especially anaphylaxis)?
Epinephrine
Anti-histamines
Corticosteroids
Albuterol
