1-Innate Immunity

Question 1

immunology

Answer 1

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

Question 2

innate immunity

definition

Answer 2

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)

Question 3

characteristics

Answer 3

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

Question 4

components

Answer 4

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

Question 5

phagocytes

Answer 5

neutrophils
macrophages
dendritic cells

first line of defense after physical barrier

Question 6

neutrophils

Answer 6

-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

Question 7

macrophages

Answer 7

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

Question 8

dendritic cells

Answer 8

involved in antigen presentation
-connect innate and adaptive immunity

Question 9

pattern recognition receptors

Answer 9

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

Question 10

toll like receptors

TLR

Answer 10

bind to PAMPs to recognize bacterial or viral products

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

Question 11

phagocytosis steps

Answer 11

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

Question 12

opsonization

Answer 12

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

Question 13

respiratory burst

Answer 13

-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

Question 14

chemotaxis

Answer 14

directed movement up a chemical gradient of a chemotactic factor

so phagocytic cell can find target microbe

Question 15

chemotactic factors

Answer 15

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

Question 16

natural killer cells

characteristics

Answer 16

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

Question 17

complement cascades

Answer 17

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

pores lead to osmotic lysis

Question 18

complement pathways

Answer 18

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

Question 19

classical pathway

complement

Answer 19

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

Question 20

alternative pathways

complement

Answer 20

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

important as host defense vs infectious pathogens

Question 21

lysis

function of complement proteins

Answer 21

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

Question 22

opsonize

function of complement proteins

Answer 22

via C3b to promote phagocytosis

Question 23

anaphylatoxins

functions of complement proteins

Answer 23

C3a, C4a, C5a

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

Question 24

chemoattractants

functio of complement proteins

Answer 24

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

Question 25

immune complex removal

function of complement proteins

Answer 25

antigen-antibody complexes coated by C3b to bind to erythrocytes and be removed by phagocytic cells in liver and spleen

Question 26

regulation of complement

Answer 26

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

Question 27

meningitis

Answer 27

if deficient in any of C5-9 then 10,000x inc chance of infection with N. meningitidis that gives you meningitis

Question 28

complement deficiencies

Answer 28

C2 most common but also have C3-4, C1q-s

inc incidence of pyogenic infections aka pus producing

immune complex diseases like lupus

Question 29

C1 inhibitor

Answer 29

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

Question 30

interferons

Answer 30

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

Question 31

acute phase proteins

Answer 31

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