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mcdb1b > immunology > Flashcards

immunology Flashcards

1
Q

How do immune cells recognize pathogens

types of recognition

A

Innate recognition
Adaptive recognition

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2
Q

Innate recognition

A

Each of a small set of receptors recognizes a molecule absent from animals, but common to a type of pathogen

recognition and response rely on traits common to groups of pathogens

look for specific 3d shapes

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3
Q

innate immune system

A

preformed barriers, tissues, cells, proteins that share common strategies across animals

first line of defense

barrier defenses and antimicrobial peptides/proteins
cellular innate defenses
lymphatic system

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4
Q

the innate immune system combined strategies can generate the

A

local inflammatory response

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5
Q

barrier defenses

A

collection of barriers
- walls
physical barrier like the skin
there are already bacteria and fungi on the skin that will compete with pathogens
lysozymes
ingested bacteria can be destroyed by acidic stomach
defensins

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6
Q

defensive barrier proteins that help when pathogens somehow enter body through openings

A

tears, mucus, saliva contain the enzyme lysozyme that attacks the cell walls of bacteria

causes lysis –> burst bacteria

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7
Q

defensins

A

positively charged small peptides that cause lysis

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8
Q

what is an interior physical barrier

A

mucous membranes
acidic pH
enzymes

epithelial lining of the GI tractd

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9
Q

defensins

A

cationic proteins
produced by neutrophils
have 3 functions:
1. neutralize toxins by binding to them and blocjing them from perorming their tasks
2. creating pores on bacterial surface with electrostatic attraction-> results in lyse
3. activate other immune cells

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10
Q

lysozyme

A

enzyme that performs lysis

breaks peptidoglycan layer over bacterial membrane
create pore
water flows in a

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11
Q

barrier defenses- antimicrobial proteins

what antimicrobial proteins exist and what do they do

A

interferons

immediately made by cells that are infected with viruses

move away from cell that made it

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12
Q

what three things can interfurons do

A

signals neighboring cells to destroy any RNA that enter them and reduces protein synthesis

signals neighboring cells to undergo apoptosis

activates immune cells which kill infected cells

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13
Q

so what occurs after viral infection

A

infected cell immediately makes interferons that move away to other cells

virus is able to continue to reproduce for a little

T-cells come and lyse the infected cells

viral load then starts to decrease

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14
Q

complement protein

A

activation of complement occurs when cell is infective

antibodies from adaptive immune system activate cascade of innate proteins that end up in a pore

lyses

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15
Q

innate system cellular defenses

A

done by white blood cells, phagocytes and lyphocytes

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16
Q

phagocytes

A

engulf and digest foreign materials and other specialized coordinate responses

two types called neutrophils and macrophages

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17
Q

all blood cells originate from

A

stem cells in the bone marrow

progenitor cell

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18
Q

dendritic cells

A

strategically positioned at points of entry to the body

engulf invaders and initiate defense responses

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19
Q

toll-like receptors

A

how you recognize non-self

key molecules that alert the immune system to presence of microbial infections

recognize pathogen associated molecular patterns(PAMS) of pathogens

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20
Q

so how do toll-like receptors actually work

A

a ligand(pathogen associated molecular pattern) fits into binding pocket of TLR and activates it

this causes a change in conformation nd activates subsequent protein transcription and translation of defense proteins –> interferons and defensins

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21
Q

inflammatory response

A

used in dealing with infection or tissue damage

bacteria make it through barier defense of skin anad is awaited by white blood cells
first resonders are mast cells and they release tumor necrosis factor, prostaglandins, and histamine which trigger inflammation

histamine diffuse away from mast cells and causes capillaries to become leaky allowing plasma and phagocytes to escape the tisssue

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22
Q

after the inflammatory response causes the capillaries to become leaky, what happens

A

complement proteins and other chemical signals attract phagocytes

neutrophils arrive first, then monocytes

macrophages engulf invaders and are responsible for most of the healing

phagocytes produce cytokines that activate other immune cells

23
Q

lymphatic system

A

sewer pipes

branching system of tiny capillaries containing larger vessels

contain lymph that conssits of fluids that accumulate outside the closed circulatory system

in lymph nodes, lymph is filtered and blood cells inspect it for pathogens

contian white blood cells

24
Q

what two types of DEFENSE mechanisms exist

A

innate defenses and adaptive defenses

25
Q

innate defenses

A

nonspecific defenses
inherited mechanisms that protect thebody from different pathogens

rapid and generalized

26
Q

adaptive defenses

A

specific defenses that protect against specific targets

some can evade innate system so second defense

slower and highly specific

specific to one pathogen at a time

27
Q

what is an antigen

A

a 3-d foreign shape that is recognized by T cells

antigens are proteins on pathogen surfaces that are composed of epitopes

antibodies uniquely bind to one epitope of antigens

virus can have multiple epitopes

28
Q

antigen presenting cells

extracellular pathogens

process of linking innate to adaptive immune system

A

antigen presenting cells include dendrites neutrophils(PMN), macrophages, and B-cells

these APCs engulf pathogens, degrade them, and display the antigen fragments on its own protein receptors, MHCII

specific helper T cells bind to this MHCII complex by the antigen fragment

binding of helper T cell promotes the secretion of cytokines by the antigen-presenting cell(APC) which stimulates proliferation of helper T cell

this proliferation produces clones of activated helper T cells

these clones have receptors of the same antigen and will also secrete other cytokines that activate B cell and cytotoxic T cells (Tc) with the same antigen specificity

29
Q

major histocompatibility complex proteins

A

two types
MHCI and MHCII

30
Q

Class I MHC pathway

A

APC can be any cell

antigen is intracellular(virus)

APC breaks down proteins in the cell and presents little peptides via MHCI complex, to cytotoxic T cells to prove your cell is not infected

31
Q

B cell vs cytotoxic T cell difference

A

B cell is for humoral immunity, the secretion of antibodies by plasma cells

cytotoxic T cells are for cell-mediated immunity which attacks infected cells (MHCI cells)

32
Q

MHC I

A

MHC I proteins are present on the surface of every nucleated cell in vertebrates

it randomly samples cytoplasm to ensure no pathogens are present

when cellular proteins are degraded in the proteasome, an MHC I protein may bind a fragment and travel to the plasma membrane to present it

cytotoxic T cells can recognize these antigens and if infected, will kill the cell

33
Q

MHC II

A

found mostly on B cells, macrophages, neutrophils, dendritic cells (apc’s)

when an antigen is phagocytosed, it is broken down and presented at the surface by MHCII

this is then recognized by helper T cells

34
Q

adaptive recognition

A

uses very specific antigen receptors on mature B or mature T cells

slight differences in amino acid sequence of antigen receptors changes whether or not cells can respond to antigens

two different branches of response in adaptive immunity:
humoral response and cell-mediated response

35
Q

humoral response

A

antibodies defend against infection in body fluids
(secretion of antibodies via B-cells)

36
Q

cell-mediated response

A

cytotoxic cells defend against infection in body cells
(kill signal via cytotoxic T cells and lysis)

37
Q

4 defining characteristics of adaptive immunity

A
  1. specificity
  2. diversity
  3. distinguish self from non-self
  4. memory
38
Q

specificity of adaptive immunity

A

immune system targets small single amino acid variations in epitopes

39
Q

memory of adaptive immunity

A

train immune system and recognize pathogens to kill it immediately if it reenters

40
Q

b-cells

A

provide diversity via variable regions with cutout that allow epitopes to bind uniquely to site of variable region

each b cell has its own unique variable region

Y shaped with two prongs/antigen binding site

41
Q

what happens when antigen with specific epitope fits in variable region

A

this activates that specific B-cell which undergoes mitosis and a clonal expansion

the b-cell will give rise to cells that secrete an antibody

antibodies can recognize specific free antigens as well as antigens on a pathogen’s surface

42
Q

T cells

A

one antigen binding site

I shaped

43
Q

how does humoral regulation work

the two step regulation

A

produces antibodies

  1. activation of T-helper cell that recognizes antigen
  2. activated T helper cell finds B cell that recognizes same antigen
44
Q

step by step of humoral regulation

A

antigen is taken up by APC and broken down

antigen piece is bound to MHCII cell and brought to cell surface where a T helper cell recognizes it

cytokines released by APC and t-helper cell, causing t-helper cell to proliferate(clonal expansion)

B-cell that engulfed the same antigen will present it via MHCII to surface where a Th cell receptor will recognize it

cytokines are released that cause B cell to proliferate and b cells can become memory cells or plasma cells

plasma cells will produce antibodies

antibodies are identical to B-cell receptors

45
Q

antibody molecules are proteins called

A

immunoglobulins

46
Q

immunoglobulins

A

comprised of 2 light chains and heavy chains

variable and constant regions

bivalent

n terminus at binding region

BCR

47
Q

two major functions of antibodies

A

agglutination

opsoniation

48
Q

agglutination

A

sticking microbes together

blockes escaoe and infection can’t spread

49
Q

opsonization

A

specific form of phagocytosis

recepptor mediated

macrophages grab onto antigens with receptors and engulf them

50
Q

two major classes of T cells

A

T-helper and cytotoxic T-lymphocytes

51
Q

cellular response occurs when

A

virus invades inside your cell

52
Q

differenec between T-helper and Cytotoxic T-lymphocytes

A

T-helper: HQ cell that regulates both humoral and cellular immune responses

cytotoxic T lymphocytes: function is to kill other cells via lysois

53
Q

general process of cellular response

A

APC will be virally infected and this virus will be broken down and presented via MHC I on cell surface

cytotoxic cell (T cell) recognizes the fragment and proliferates

T cell receptoor recognizes antegenic fragment bound to a MHC I protein of a separate infected cell and T cell releases perforin

perforin creates pores that result in lysis

mcdb1b (10 decks)

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