1-Innate Immunity Flashcards

1
Q

immunology

A

study of host defenses vs infectoius disease and neoplasm and the undesirable consequences of immune interactions

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2
Q

innate immunity

definition

A

1st line of defense vs microorgs

defense mechanisms that are always present and ready to combat microbes, stand by

keep person alive long enough for more potent response to dev (adaptive immunity)

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3
Q

characteristics

A
  1. NOT antigen specific
  2. exist prior to antigen exposure
  3. not enhanced following exposure
  4. always available bc not depend on clonal expansion of antigen specific cells
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4
Q

components

A
  1. phagocytes
  2. natural killer cells
  3. complement proteins
  4. interferons
  5. acute phase proteins
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5
Q

phagocytes

A

neutrophils
macrophages
dendritic cells

first line of defense after physical barrier

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6
Q

neutrophils

A

-polymorphonuclear cells/neutrophils (PMN)
-small granules
-either circulating pool or marginal pool of blood and will stay there until recruited

marginal loosely bound to endothelial cells

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7
Q

macrophages

A

primary functions are NOT immune
1. remove dead cells (wound healing)/inhaled particles/aged RBCs
2. secrete hormones to reg granulocyte and erythrocyte pools

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8
Q

dendritic cells

A

involved in antigen presentation
-connect innate and adaptive immunity

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9
Q

pattern recognition receptors

A
  1. PAMP-pathogen associated molecular pattern molecular structures syn by microbial pathogens i.e. LPS (gram neg) or peptioglycan (gram pos)
  2. DAMP- damage associated molecular pattern endogenous molecules syn or released from damaged or dying cells i.e. heat shock proteins
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10
Q

toll like receptors

TLR

A

bind to PAMPs to recognize bacterial or viral products

TLR2 = bacterial peptidoglycan
TLR4 = LPS
-both @ plasma membrane

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11
Q

phagocytosis steps

A
  1. attachment- nonspecific antigens, if encapsulated in sugar/polysacc coating then must be opsonized
  2. ingestion- pseudopods/plasma membrane wraps around particle until fuse together/zip = phagosome once internalized
  3. digestion- lysosomes fuse with phagosomes = phagolysosome to degrade microbial components
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12
Q

opsonization

A

coating of a microbe with antibody (IgG) or complement (C3b) to facilitate phagocytosis bc phagocytic cells have receptors for IgG and C3b

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13
Q

respiratory burst

A

-inc consumption of oxygen during phagocytosis bc NADPH oxidase = superoxide anion
-also hydroxyl radical, singlet oxygen, hypochlorite are toxic just not made by NADPH

damage membranes, proteins, nucleic acids

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14
Q

chemotaxis

A

directed movement up a chemical gradient of a chemotactic factor

so phagocytic cell can find target microbe

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15
Q

chemotactic factors

A
  1. C5a
  2. leukotriene B4 (from arachidonic acid)
  3. chemokines (from macrophages @ site of infection)
  4. bacterial lipids and proteins
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16
Q

natural killer cells

characteristics

A
  1. large granular lymphocytes
  2. not specifically recognize antigens
  3. kill virus infected cells and tumor cells via perforin that forms pores in plasma membranes of target cells
  4. mediate antibody-dependent cell mediated cytotoxicity (ADCC)
  5. highly activated when exposed to interleukin-2 or interferons

either target cell itself or antibodies

17
Q

complement cascades

A

sequentially activated soluble serum proteins to make pores in cell surface and opsonize antigens

pores lead to osmotic lysis

18
Q

complement pathways

A
  1. alternative- initiation @ microbe
  2. classical- initation @ antibody
  3. lectin- mannose binding lectin, dont need to know

all paths end with membrane attack complex (MAC) that makes pores

19
Q

classical pathway

complement

A

activation requires 2 IgGs spaced apart OR 1 IgM pentamer for antigen to bind and start complement, free antibody will not work

IgM more efficient than IgG at activating

20
Q

alternative pathways

complement

A

don’t need antibody to initiate can just bc directly on microbial surface

important as host defense vs infectious pathogens

21
Q

lysis

function of complement proteins

A

C5-9 = membrane attack complex aka MAC > osmotic lysis via pores

22
Q

opsonize

function of complement proteins

A

via C3b to promote phagocytosis

23
Q

anaphylatoxins

functions of complement proteins

A

C3a, C4a, C5a

all bind to receptors on mast cells and basophils to release histamine

24
Q

chemoattractants

functio of complement proteins

A

by C3a and C5a to stimulate chemotaxis of neutrophils to site of production

25
immune complex removal | function of complement proteins
antigen-antibody complexes coated by C3b to bind to erythrocytes and be removed by phagocytic cells in liver and spleen
26
regulation of complement
DAF (decay accelerating factor) compete with C3b to prevent formation of convertases CD59 prevent binding of C9 to complete MAC if not have either then proxysmal nocturnal hemoglobinuria aka lysis of RBCs by complement | low yield
27
meningitis
if deficient in any of C5-9 then 10,000x inc chance of infection with N. meningitidis that gives you meningitis
28
complement deficiencies
C2 most common but also have C3-4, C1q-s inc incidence of pyogenic infections aka pus producing immune complex diseases like lupus
29
C1 inhibitor
results in hereditary angioedema (HAE) so when emotional stress or trauma complement activated + bradykinin edema in skin and larynx (life threatening) restricts spontaneous activated of C1 in plasma and regs hageman factor that gives rise to HAE if no inhibitor
30
interferons
type 1 interferon = alpha + beta IFN -inhibits viral replication via paracrine action -enhance cytolytic capability of NK cells -inc cellular expression of class I MHC molecules
31
acute phase proteins
syn by liver in response to interleukin 6 from macrophages after infection into bloodstream C-reactive protein, mannose binding lectin = opsonins -CRP also activate classical complement by C1q fibrinogen, serum amyloid A protein too