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MicroBio > Exam 3 > Flashcards

Exam 3 Flashcards

1
Q

Genetic engineering

A

Using in vitro techniques to alter genetic material in the laboratory

Basic techniques include: restriction enzymes, gel electrophoresis, nucleic acid hybridization, nucleic acid probes, molecular cloning, cloning vectors

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2
Q

Nucleic acid hybridization

A

Base pairing of single strands of DNA or RNA from two different sources to give a hybrid double helix

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3
Q

What is a nucleic acid probe?

A

A segment of single-stranded DNA that is used in hybridization and has a predetermined identity

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4
Q

Southern blot

A

a hybridization procedure where DNA is in the gel and probe is RNA or DNA

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5
Q

Northern blot

A

a hybridization procedure where RNA is in the gel, probe is RNA or DNA

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6
Q

What are the components of PCR?

A

DNA sample, primers, nucleotides, taq polymerase, mix buffer, PCR tube

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7
Q

What is the process of PCR?

A
  1. Denaturing (95oC - strands separate)
  2. Annealing (55oC - primers bind template)
  3. Extension (72oC - synthesize new strand)
  4. Repeat, repeat, repeat
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8
Q

What are applications of PCR?

A

Phylogenetic studies

Surveying different groups of environmental organisms

Amplifying small amounts of DNA

Identifying a specific bacteria

Looking for a specific gene

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9
Q

RTPCR

A

reverse transcriptase, RNA snapshot

laboratory technique combining reverse transcription of RNA into DNA (in this context called complementary DNA or cDNA) and amplification of specific DNA targets using polymerase chain reaction (PCR)

It is primarily used to measure the amount of a specific RNA

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10
Q

qPCR

A

double strand dye

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11
Q

Molecular cloning

A

isolation and incorporation of a piece of DNA into a vector so it can be replicated and manipulated

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12
Q

Three main steps of gene cloning

A
  1. Isolation and fragmentation of source DNA
  2. Insertion of DNA fragment into cloning vector
  3. Introduction of cloned DNA into host organism
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13
Q

Steps for screening a library by colony hybridization (7 steps)

A

Start with a master plate with colonies of bacteria containing cloned segments of foreign genes

  1. Make replica of master plate on nitrocellulose fiber
  2. Treat filter with detergent (SDS) to lyse bacteria
  3. Treat filter with sodium hydroxide (NaOH) to separate DNA into single strands
  4. Add radioactively labeled probes
  5. Probe will hybridize with desired gene from bacterial cells
  6. Wash filter to remove unbound probe and expose filter to X-ray film
  7. Developed film is compared with replica of master plate to identify colonies containing gene of interest
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14
Q

Gene probes

A

small DNA sequences (oligonucleotide) complementary to only the gene of interest that is “labeled” for detection (such as radioactivity)

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15
Q

Electroporation

A

a technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane

This may allow chemicals, drugs, electrode arrays or DNA to be introduced into the cell

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16
Q

Microbiota

A

microorganisms present at a more defined region of our body, can be disturbed by things such as antibiotics

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17
Q

Human microbiome

A

assemblage of microorganisms on and in the diverse regions/habitats of our body

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18
Q

There are _____ bacteria than cells in the body

A

more

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19
Q

There are _____ bacteria than people on the planet

A

more

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20
Q

Metabolic activity is a _____ organ

A

virtual

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21
Q

The human GI tract contains ____ to _____ microbial cells

A

10^13, 10^14

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22
Q

Microbiota is influenced by ____ and the _______ in the area

A

diet, physical conditions

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23
Q

The _____ of the stomach and duodenum prevent many organisms form colonizing here

A

acidity, they have a pH of ~2

However there is a rich microbiome in the healthy stomach

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24
Q

What types of microbiota are found in the large intestine?

A

10^12 cells/g - live “fermentation vessel”

Facultative aerobes (E. coli) in low numbers, use up rest oxygen

Mainly obligate anaerobes such as clostridium and bacteroides

Very few microbial eukaryotes (yeast Candida albicans)

no protists

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25
Q

What microbiota are found in the stomach?

A

10^4 cells/g

Firmicutes, Bacteroidetes, and
Actinobacteria, in acidic lumen

Proteobacteria in gastric mucosa where pH is already close to 7

Helicobacter pylori is present in 50% of people, risk of chronic inflammation

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26
Q

What microbiota are found in the small intestine?

A

10^8 cells/g

becomes gradually less acidic and more anoxic

mainly anaerobic Fusobacterium (long slender rods), attached with one end to intestinal wall

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27
Q

Where are microbiota found in the large intestine?

A

bacteria are in lumen and outer mucus layer

not in inner, partially aerobic mucus layer, contains also antimicrobial peptides to protect gut mucosa

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28
Q

Bacteria make vitamins ____, _____, and ____ out of 20 amino acids for us that we can’t make

A

K, B12, 9

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29
Q

Cell _____ within intestine replaces lost microbes

A

doubling (1-2 divisions/day)

Material leaves human body after ~24 hours, with ~10^13 bacteria/day

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30
Q

The vast majority (~98%) of all human gut phylotypes fall into one of three major bacterial phyla:

A

firmicutes, bacteroidetes, and proteobacteria

Individual people may have >90% firmicutes, >90% bacteroidetes, or a mix of the two

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31
Q

Individuals are one of three enterotypes:

A
  1. Bacteroides-dominated (bacteroidetes)
  2. Prevotella-dominated (bacteroidetes)
  3. Ruminococcus-dominated (firmicutes)

Not correlated with ethnicity or diet, but species of individual’s gut microbiome is often shared among family members

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32
Q

Gut microbiome influences our ______, ________, ________, etc.

A

heath, propensity for leanness/obesity, response to drug therapy

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33
Q

The immune system does not properly develop in the absence of ___________________

A

microbial stimulation

Early life exposure to a variety of microorganisms is essential to develop tolerance for beneficial microorganism, and to recognize harmful ones as foreign

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34
Q

Excessive hygiene with infants and during early childhood results in:

A

poorly trained immune system and frequent inflammatory response to harmless bacteria, promotes autoimmune conditions (allergies)

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35
Q

Germ-free mouse study

A

Studies in germ-free (GF) animals show the crucial role of gut microbiota in the development and maturation of the immune system

Immaturity of gut-associated lymphoid tissue (Galt) in GF mice

Decreased serum immunoglobulin levels (“antibodies”)

Underdeveloped, smaller thymus and spleen

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36
Q

Gnotobiotic mice

A

refers to mice in which every microorganism present is defined

Germ-free mice are one class of gnotobiotic animals, but mice associated with defined bacterial communities (e.g. Altered Schaedler’s Flora) are considered gnotobiotic

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37
Q

Gut colonization

A

Not yet completely understood

Significant difference in naturally born vs. caesarian section in infants

Also, breastfeeding vs. formula influences gut microbiota and immune system development

Gut of naturally-born, breast-fed infants contain mainly bifidobacteria (actinobacteria) - anaerobic fermenters, make vitamin K, B6, and B7

Microbiota changes several times until it establishes adult-like at 3 years

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38
Q

Protective functions of gut microbiota

A

Pathogen displacement

Nutrient competition

Receptor competition

Production of anti-microbial factors (bacteriocins, lactic acids)

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39
Q

Structural functions of gut microbiota

A

Barrier fortification

Induction of IgA

Apical tightening of tight junctions

Immune system development

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40
Q

Metabolic functions of gut microbiota

A

Control IEC differentiation and proliferation

Metabolize dietary carcinogens

Synthesize vitamins (biotin, folate)

Ferment non-digestible dietary residue and endogenous epithelial-derived mucus

Ion absorption

Salvage of energy

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41
Q

Gut-associated lymphoid tissue (GALT)

A

the key antigen sampling and adaptive immune inductive sites within the intestinal wall

Human GALT includes the multi-follicular Peyer’s patches of the ileum, the vermiform appendix, and the numerous isolated lymphoid follicles (ILF) which are distributed along the length of the intestine

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42
Q

A wide range of circumstances can influence bacterial balance:

A

Age and diet

Susceptibility to infections

Use of antibiotics or other drugs

Excess alcohol

Immunologic status of the host and stressors

Exposure to toxic substances

The GIT PH

Transit time

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43
Q

Probiotics

A

A usually dairy food or a dietary supplement containing live bacteria that replace or add to the beneficial bacteria normally present in the gastrointestinal tract

Examples: lactobacillus, bifidobacteria, enterococcus, lactococcus, streptococcus, saccharomyces/yeast

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44
Q

Probiotic mechanism of action

A

Metabolic end-products, such as SCFAS

Competitive effects from occupation of normal colonization sites

Direct antagonism through natural antimicrobial compounds (bacteriocins)

Competition for nutrients

Enhancement of immune system

Increase absorption of vitamins and minerals

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45
Q

Prebiotics

A

A non-digestive food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria

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46
Q

Prebiotics block pathogens early on by:

A
  1. Non-digestibility (gut bacteria convert SCFA)
  2. Selective fermentation by one or a limited number of potentially beneficial bacteria in the colon
  3. Alteration of the composition of the colonic microbiota towards a healthier composition
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47
Q

Short chain fatty acids (SCFA or VFAs)

A

Derived from prebiotics undigestable oligosaccharides

Main source of energy for colonic epithelial cells

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48
Q

Maternal immune activation (MIA)

A

Changes mouse pup’s gut microbiota induced by poly(I:C), caging!

Pups exhibit autism-like disorder

Adding back B. fragilis increases 4-EPS ameliorates ALD

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49
Q

Inflammatory bowel disease (IBD)

A

chronic inflammation of GI tract

diarrhea, blood in the stool, weight loss, and abdominal pain

not caused by a specific pathogenic microorganism

an imbalance between immune system and normal gut flora

microbial community exhibits significantly less functional capacity

IBD cause and transmission not well understood

possible: early antibiotic treatment, or, protein-rich diet

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50
Q

Obesity

A

excessive amount of body fat

indirectly increases your risk of other diseases and health problems, such as heart disease, diabetes, high blood pressure and certain cancers

not caused by a specific pathogenic microorganism

in mice: energetic imbalance of microbial gut flora

more Firmicutes and methanogenic Archaea

stronger H2-consumption leads to more turnover in fermentation

increased production of acetate, propionate, butyrate, … taken up by host

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51
Q

Transfer of obese conditions

A

A microbiota transplant can transfer the obese gene to organisms

Mice are coprophagic, and mice in a cage can transfer the obese gene to each other that way

The microbiota mean something and can be transferred

Research with humans is challenging, less controllable diet, behavior, genotype

Account for side symptoms, e.g., hypertension, glucose intolerance, diabetes

Contradicting hypotheses, e.g., increased VAFs would bind to fatty acid receptors in gut, signaling feeling of “full”

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52
Q

Healthy gut is maintained by ___________

A

akkermansia muciniphila, without it you have a leaky gut

53
Q

Innate immunity

A

Built-in capacity of the immune system of multicellular organisms to target pathogens that are seeking to colonize the host

Does not require previous exposure to pathogen or its products

targets common pathogens and/or their products

Responds within hours, non-inducible

Does not require pre-exposure

Does not generate memory

Driven by phagocytes (white blood cells able to ingest, kill, and digest pathogens)

54
Q

Three types of innate immunity

A

Physical (skin, nasal hair, eyelashes and eyelids, mucous membranes, mucocilliary clearance, urination)

Chemical (low pH, antimicrobial molecules)

Biological (microbiome)

55
Q

Opportunistic pathogens

A

Many elements of the normal flora may act as opportunistic pathogens, especially in hosts rendered susceptible by rheumatic heart disease, immunosuppression, radiation therapy, chemotherapy, MRSA

56
Q

Obligate pathogens

A

Never part of normal flora, always cause disease, usually require host for multiplication

HIV, Hansen’s disease (leprosy)

57
Q

Successful infection is:

A

influenced by virulence of the pathogen and health condition of the host

58
Q

What are the steps of infection?

A
  1. Exposure to pathogens
  2. Adherence to skin or mucosa
  3. Invasion through epithelium
  4. Multiplication/colonization - growth and production of virulence factors and toxins
  5. Enter bloodstream (go on to cause disease)
59
Q

Steps of bacteria causing disease

A

1a. Toxicity - toxin effects are local or systemic

OR

1b. Invasiveness - further growth at original and distant sites

  1. Tissue or systemic damage
60
Q

Adherence

A

ability of bacteria to stick to host cell

3D shape that determines host range and success of an infection

61
Q

Chromosomal island

A

big hunk of DNA that can be passed through conjugation

Several genes that direct invasion are clustered together as pathogenicity islands

62
Q

Presence of __________ differentiates virulent from non-virulent strains in streptococcus pneumoniae

A

slime capsule

Evade phagocytosis of white blood cells and severely infect lung tissue

63
Q

Presence of __________ differentiates virulent from non-virulent strains in Escherichia coli

A

fibriae

attach to mucus membrane of urinary tract and implement infection

64
Q

Presence of __________ differentiates virulent from non-virulent strains in Neisseria gonorrhoeae

A

cell surface protein/adhesin, binds only to host cell surface proteins found in genitourinary tract, eye, rectum, and throat

65
Q

All gram negative bacteria share a particular virulence factor:

A

Lipopolysachharide (LPS)

A structural part of the outer membrane, replaces most of phospholipids in outer half of outer membrane

Is released when:
1. Secreted as part of the normal physiological activity during (outer) membrane vesicle trafficking while also excreting other virulence factors and proteins

  1. Set free passively when cells die (attack from immune system) and cell structures get disintegrated
66
Q

Lipid A of the LPS layer

A

is important for host receptor recognition

Lipid A chemistry differs among distinct bacterial species

The exact LPS structure, and especially lipid A structure, determines immunogenicity

Can cause strong or weak inflammatory reactions

67
Q

LPS layer causes dysregulation of:

A

immune system (induces inflammation)

clotting cascade

blood pressure regulation

Results in fever, altered white blood cell count, hemorrhaging/clotting, lowered blood pressure, shock, death

68
Q

Exotoxins

A

Inhibit host cell function or kill host cells

Proteins released from the pathogen cell as it grows

Three categories: cytolytic toxins, AB-toxins (active (A) domain and a binding (B) domain), superantigen toxins

69
Q

Cytolytic toxins

A

Work by degrading cytoplasmic membrane integrity, causing cell lysis and death

Hemolysin, leukocidin, phospholipase

70
Q

Hemolysin

A

Toxin that lyses red blood cells

E.g. staphylococcal alpha-toxin

71
Q

Leukocidin

A

Toxin that lyses white blood cells

72
Q

Phospholipase

A

Hydrolyze phospholipids (membranes) into fatty acids

73
Q

Diphtheria AB-exotoxin: blockage of protein synthesis

A

Corynebacterium diphtheriae

Causes thick covering in the back of the throat

Can lead to difficulty breathing, heart failure, paralysis, and even death

74
Q

Neurological exotoxins: botulinum and tetanus toxins

A

Clostridium tetani and clostridium botulinum produce potent AB-exotoxins that affect nervous tissue

Botulinum toxin consists of several related AB-toxins that are the most potent biological toxins known

75
Q

Enterotoxin

A

AB-exotoxins whose activity affects the small intestine

Generally cause massive secretion of fluid into the intestinal lumen, resulting in vomiting and diarrhea

Cholera toxin in vibrio cholerae (lysogen)

76
Q

Superantigens

A

Cause an overstimulation of the immune system

Can lead to shock and death

Generally due to localized infection, but with systemic effects (staphylococcus aureus toxins shock syndrome)

In severe cases cause bacteremia or septicemia (streptococcus pyrogenies toxic shock syndrome)

Specifically, it causes non-specific activation of T-cells resulting in polyclonal T-cell activation and massive cytokine release

Fever, functional disruption of kidney, liver, etc

77
Q

Invasion

A

Pathogens produce enzymes that:
enhance virulence by breaking down or altering host tissue to provide access to nutrients (hyaluronidase)

protect the pathogen by interfering with normal host defense mechanisms (coagulase, staph aureus fibrin coat)

78
Q

Virulence can be estimated from experimental studies of the ________

A

LD50 (lethal dose50)

The amount of an agent that kills 50% of the animals in a test group

Highly virulent pathogens show little difference in the number of cells required to kill 100% of the population

79
Q

Compromised host

A

One or more resistance mechanisms are inactive

Genetic predisposition, or a permanent primary infection (e.g. HIV)

Temporary immune-suppressing conditions such as pregnancy, or undergoing medical procedures (e.g. surgery) predispose individuals to develop disease

Nosocomial infections affect nearly 2 million people each year

Chemotherapy induced neutropenia (neutrophils WBC first responders)

80
Q

Attenuation

A

The decrease or loss of virulence

Attenuated strains of various pathogens are valuable to clinical medicine because they are often used as vaccines

May be a result from keeping a strain in laboratory culture over long periods of time

No selective pressure for expressing/keeping pathogenicity genes

81
Q

Adaptive immunity

A

The acquired ability to recognize and destroy a specific pathogen or its products

Dependent on previous exposure to the pathogen or its products (specificity)

Directed toward an individual molecular component of the pathogen (antigen)

Responds after days

Induced by innate response

Requires pre-exposure

generates immune memory

Driven by lymphocytes - white blood cells for making antibodies, mark pathogens for destruction

82
Q

Natural host resistance

A

Normal microbiota helps host resist pathogens, particularly on the skin and in the gut

Pathogens do not easily infect tissues because the harmless microbes limit available nutrients and sites for infection (competitive exclusion)

The ability of microbes to cause disease varies between species (e.g variable sensitivity to rabies, host range)

83
Q

The lymphatic system

A

Separate circulatory system that drains lymph fluid from extravascular tissues

Blood is pumped through arteries and capillaries and returns from the body through veins

In capillary beds, leukocytes and solutes pass from blood into the lymphatic system

Lymph nodes contain high concentrations of immune system cells

84
Q

Leukocytes (buff coat)

A

Nucleated white blood cells

About 0.1 percent of the cells in blood are white blood cells

Include lymphocytes, granulocytes, and monocytes

85
Q

Whole blood is composed of ________ and ________

A

Plasma and cells

Plasma contains proteins and other solutes

86
Q

Serum

A

The portion of blood that is not cells or clotting proteins

87
Q

Lymphocytes

A

Specialized leukocytes involved exclusively in adaptive immune response

B cells: originate and mature in bone marrow

T cells: originate in bone marrow, but mature in thymus

88
Q

Tissue damage and chemokine release

A

Tissue damage triggers the recruitment of a large number of phagocytes

Resident leukocytes and damaged cells release cytokines, or chemical mediators, that allow communication between white blood cells

Release of cytokines and chemokines draws macrophages and neutrophils to the area as they leave circulation (extravasion)

89
Q

Pathogen-associated molecular patterns (PAMP)

A

Pathogens have structures and molecules not found in or on host cells (e.g. peptiglycan, flagellin, DSRNA)

LPS is a pamp

Pattern recognition receptors

Leukocytes have membrane bound or soluble proteins that recognize pamps

90
Q

Signal transduction in phagocytes

A

Upon encountering a pathogen-associated molecular pattern, toll-like receptors (TLR) will send a signal to the nucleus

Each TLR on a human phagocyte recognizes and interacts with a specific pamp

At least 9 TLRs in humans interact with cell surface and soluble pamps from viruses, bacteria, and fungi

91
Q

Inhibiting phagocytes

A

Some pathogens can survive the phagolysosome

Mycobacteria tuberculosis produces carotenoids to neutralize singlet oxygen and has a waxy cell wall that absorbs free radicals, this pathogen lives and divides within phagocytes

Some pathogens, such as Streptococcus pyogenes produce leukocidins, which kill white blood cells (dead white blood cells are found in pus)

Lastly, some pathogens contain a capsule, which makes it difficult for the phagocyte to engulf them. Host antibodies can counteract this, which is why pneumococcal vaccines are effective in preventing pneumonias caused by Streptococcus pneumoniae

92
Q

Steps of antibody production in B cells

A
  1. BCR (B cell surface antibodies) recognizing its specific epitope on pathogen or toxin; B cell ingests the antigen (part of entire pathogen) via phagocytosis
  2. Digestion and presentation of (several) antigens of the encountered pathogen or toxin on their surface (MHC II) to T helper cells
  3. T helper cell produces cytokines that stimulate division of antigen-reactive B cells, which differentiate into thousands of plasma cells
  4. Secretion of large amounts of antibodies of identical antigenic specificity
93
Q

Induction of inflammation

A

non-specific reaction to damage

symptoms at the site of infection: redness, swelling, pain, heat

94
Q

Aims of inflammation

A

Isolation of site

Destruction of invaders

Removal of damaged cells

**Can also inadvertently result in considerable damage to healthy tissue, particularly key organs, such as lungs and brain tissue

95
Q

Fever

A

Certain cytokines, particularly IL-1, will cause the host’s body temperature to rise, causing a fever

Fever-causing cytokines are called pyrogens because they generate heat

Fever is beneficial because it increases circulation rate, which allows leukocytes to get to the site of infection

Also beneficial because some pathogens cannot tolerate increased temperature

Associated with an increase in transferrins, which sequester iron, keeping it away from pathogens and limiting their growth

96
Q

Systemic inflammation and septic shock

A

Widespread (systemic) inflammation can lead to shock as the increased vascular permeability decreases a host’s blood pressure, which can cause damage to multiple organs at the same time

Gram-negative bacteria are particularly dangerous because they contain LPS, which triggers a pro inflammatory response from leukocytes as their toll-like receptors are activated. This leads to a cytokine storm, which can be fatal

97
Q

Complement system (C’)

A

Set of circulating, inactive proteins that are sequentially activated in response to a pathogen

Initiated when complement binds to antibodies that are attached to a pathogen

C1 cleaves C2 and C4 to form C2A-C4B, otherwise known as C3 convertase

Convertase breaks C3 into C3B, which binds to the target cell and C3A, which diffuses into the surrounding area and serves as a chemoattractant

98
Q

Opsonization

A

C3B of complement system coating a target makes it easier for the phagocytes to engulf it

99
Q

Membrane attack complex (MAC)

A

With C3B added, the C3 convertase also binds C5, leading to C5A being released and C5B binding to the cell

100
Q

Monnose-binding lectin (MBL) and alternative pathways

A

Rely on innate mechanisms rather than antibodies to activate the complement pathways

While they start at a different place in pathway, all three complement systems end with opsonization, direct attack, and recruitment of phagocytes

Some chemoattractants (C5A and C3A) are considered anaphylatoxins because they can lead to immune over activation and potentially anaphylactic shock

101
Q

Major histocompatibility complexes (MHC)

A

All nucleated cells in the body contain these surface proteins (MHC type I)

Purpose is to present small fragments of protein

Many viruses force body cells to decrease or even stop their expression of MHC I (happens also during differentiation into tumor cell)

This change will be noticed by both leukocytes of the innate immune system (natural killer cells) and leukocytes of the adaptive immune system (cytotoxic T cells)

102
Q

MHC I cells present ________

A

self-protein (“I belong to the body”)

103
Q

MHC II cells present _______

A

antigens (“I found this foreign thing”)

Are only on special immune cells: phagocytes (macrophages and dendritic cells) and B cells (cells of the adaptive immune system)

104
Q

Natural killer (NK cells)

A

Cytotoxic lymphocytes

Recognize cells that do not display MHC I

No MHC and a stress protein

NK kills target (likely old, virally infected, cancer cell)

105
Q

Granzyme

A

Enzyme that induces programmed cell death (apoptosis)

106
Q

Perforin

A

Chemically and functionally similar to C9, pokes holes in the target membrane

107
Q

Interferons

A

Small cytokine proteins that are produced by virally infected cells

Interferons serve as a warning system and prevent viral replication by stimulating the production of antiviral proteins in uninfected cells once they receive the interferon signal from infected cells

108
Q

Antibody functions

A

Most of all cases: marking pathogen’s surface for destruction (phagocytes have unspecific antibody recognizing receptors, phagocytosis of IG-coated cell or virus)

Interfering with pathogen’s outer structures, inhibiting infection (e.g. antibodies in mucous membranes hinder influenza virus to attach host cells)

Binding toxins, neutralizing their effect (e.g. antibodies circulating in blood and lymph serum block their binding to host cell receptors)

109
Q

Cytotoxic T cell

A

kill cell with antigen (release granule contents that kill target cell by apoptosis)

110
Q

T helper cell binding MHC II

A

production of cytokines/interleukins

111
Q

Natural active immunity

A

getting a disease and recovering

112
Q

Natural passive immunity

A

passing antibodies to nursing infants through breast milk

113
Q

Artificial active immunity

A

receiving a vaccination shot and developing immunity

114
Q

Artificial passive immunity

A

Receiving pre-formed antibodies (antiserum)

115
Q

Type I (intermediate) allergies

A

Increase or decrease of blood pressure or heart rate

Mild or life threatening (anaphylaxis)

Pollen, mold, nuts, shellfish, insect venom

Immune system alert through mucous membranes of lungs or gut

Antibody-mediated

116
Q

Type IV (delayed) allergies

A

Often after contact with skin (contact dermatitis)

Itchiness, reddening, edema, tissue damage, blisters

Jewelry, cosmetics, poison ivy, latex

Cell-mediated

117
Q

Immunodeficiency

A

Active adaptive immunity is critical for infectious disease resistance

Animals (humans included) with deficiencies in B cells are prone to bacterial infections, while those with T cells are prone to viral infections and cancers

118
Q

Severe combined immune deficiency (SCID)

A

Serious, congenital deficiency of both B and T cells

Patients live a restricted life, limiting their exposure to pathogens

X-SCID interlukin receptor missing, expresses on T, B, and NK cells

Omen syndrome RAG gene mutations (recombination activating gene)

119
Q

Acquired immunodeficiency syndrome (AIDS)

A

Caused by HIV infection that progresses and kills CD4 + T cells

Patients are prone to opportunistic infections and cancer, since they are deficient in T cell help

If CD4 count stays the same, HIV medication is working

If CD4 count drops, virus has mutated and medication is no longer working

120
Q

Antigen-positive relapse

A

One of two main forms of disease relapse after car-T cell infusions

In the early phase and antigen escape relapse in a later phase

The disease relapse of antigen-positive cells is closely related to car-T cell persistance

Factors that affect the persistence of car-T cells require further exploration

CD137, which is significantly different from the CD28 costimulatory domain, has been shown to stimulate fatty-acid oxidation in metabolism and to increase the central memory phenotype, thereby improving car-T cell persistence

121
Q

Antigen escape

A

one of two main forms of disease relapse after car-T cell infusions

Including antigen loss or downregulation

Alternative splicing is the primary cause of CD19 antigen loss and induces the generation of CD19 isoforms that gradually develop into dominant clusters under the strong immune pressure

Minimum antigen density threshold is required for car-T cells to achieve therapeutic efficacy. In preclinical models, Sadelain et al demonstrated that car-T cells extract and transfer target antigens into T cells via trogocytosis, which leads to a reversible decrease in antigen density

Researchers have also verified that combinatorial multi-antigen-targeted strategies could effectively prevent the tumor escape caused by low antigen density that results from car-T cell trogocytosis

122
Q

Cytokine release syndrome/storm

A

A condition that may occur after treatment with some types of immunotherapy, such as monoclonal antibodies and car-T cells

Caused by a large, rapid release of cytokines into the blood from immune cells affected by the immunotherapy

123
Q

Monoclonal antibodies

A

Produced by isolating single clones of B cells that are fused with cancer cells to make immortalized cell lines that produce a single type of antibody

Clinical diagnostic tests that use MABs include immunological typing of bacterial pathogens, identification of cells containing foreign surface antigens and highly specific blood and tissue typing, and are also used to detect and treat human cancers

124
Q

Direct agglutination

A

Results when soluble antibody causes clumping due to interaction with an antigen that is an integral part of the surface of a cell or other insoluble particle

Used for the classification of antigens found on the surface of red blood cells

125
Q

Passive agglutination

A

The agglutination of soluble antigens or antibodies that have been adsorbed or chemically coupled to cells or insoluble particles (e.g. latex beads, charcoal)

Reactions can be up to five times more sensitive than direct agglutination tests

126
Q

Enzyme immunoassay (EIA) or enzyme-linked immunosorbent assay (ELISA)

A

Very sensitive immunological assay

Widely used in clinical diagnostic and research applications

EIAs employ covalently bonded enzymes attached to antibody molecules

Rapid tests are similar to EIAS

Both allow detection of antigen-antibody complexes

127
Q

Rapid tests

A

Similar to EIAs except that results can often be reported within minutes instead of hours

Provide point-of-care diagnostics but are generally not as specific or sensitive

Reagents are absorbed to support material

Body fluid is applied to the support matrix

Matrix contains a soluble antigen conjugated to a colored molecule (chromophore)

Matrix also contains a line of fixed antigen which antibodies bind to, detect color change

128
Q

Immunoblot (western blot)

A

Electrophoresis of proteins, followed by transfer to a membrane and detection by addition of specific antibodies

Immunoblot methods detect antibodies to specific antigens or the antigens themselves

Detects anti-HIV antibodies, confirmatory test for HIV rapid

MicroBio (5 decks)

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