Innate Immunity

Question 1

cells of the second line of defense

Answer 1

innate immune cells
processes of non-specific defense
antimicrobial mediators/immune activators

Question 2

innate immune cells consist of

Answer 2

macrophages, neutrophils, eosinophils, basophils, NK cells, dendritic cells, mast cells

Question 3

process of non-specific defense consists of

Answer 3

phagocytosis, pattern recognition receptor activation, inflammation

Question 4

antimicrobial mediators/immune activators consist of

Answer 4

cytokines, interferons, TNF, IL-6; chemokines, complement cascade

Question 5

cells of innate immunity

Answer 5

granulocytes: contain small granules inside them to provide rapid soluble factor release (eosinophils, basophils, mast cells, neutrophils)

phagocytes: consume and kill pathogens intracellularly, and some participate in adaptive immune engagement (neutrophils, macrophages, dendritic cells)

Question 6

similar to first line of defense, innate immune cells use _____ _______ to eliminate non-self objects

Answer 6

chemical defense

combination of extracellular and intracellular efficacy provides direct cell killing

Question 7

neutrophils

Answer 7

-40-60% of leukocytes
-short-lived
-early responders
-work as phagocytes
-granules contain lytic enzymes and antimicrobial peptides
-generates reactive oxygen and nitrogen species (peroxide and hypochlorite)
-form neutrophil extracellular traps

Question 8

mast cells

Answer 8

-early warning cells that quickly release granules in response to signals from bacteria, viruses

Question 9

eosinophils

Answer 9

-parasitic infection
-break down outer coating of parasite and kill organisms

Question 10

macrophages

Answer 10

-monocyte precursors are recruited and differentiate into dendritic cells or macrophages
-phagocytes
-antigen-presenting cells (APCs), stimulate adaptive immune responses

Question 11

pathogen-associated molecular patterns (PAMPs)

Answer 11

-molecular signatures that are not present in normal mammals
-recognized by pattern recognition receptors (PRRs)
-stimulate an innate immune response, including cytokine and chemokine production

Question 12

types of PRRs

Answer 12

-toll-like receptors: many ligands
-NOD-like receptors: intracellular bacteria
RIG-I/MDA5: dsRNA
cGAS/STING: cytoplasmic DNA
PKR - dsRNA

Question 13

innate immunity - phagocytosis

Answer 13

1. bacterium binds to PRRs on membrane evaginations called pseudopodia
2. bacterium is ingested, forming phagosome
3. phagosome fuses with lysosome
4. bacterium is killed and then digested by low pH-activated lysosomal enzymes
5. digestion products are released from cell

Question 14

opsonization

Answer 14

enables phagocytosis
-antibodies bind to antigens + complement
-achieves binding with macrophage receptors to achieve phagocytosis
-Fc receptor and C3b receptor (complement fragments)
CHANGES THE SURFACE OF AN ANTIGEN TO ENHANCE PHAGOCYTOSIS

Question 15

role of antibodies in innate immune activation

Answer 15

-antigen binding
-complement activation
-activate phagocytes and neutrophils for inflammation, opsonization and phagocytosis

Question 16

multi-component opsonization

Answer 16

-increases the efficacy of innate immune function
- binding through multiple mechanisms increases the effective response
-C3b receptor and Fc receptor

Question 17

what does the complement pathway do

Answer 17

indirectly triggers inflammation and fever

Question 18

ways that the complement pathway is activated

Answer 18

classical pathway: antibodies bind to foreign substances and begins the complement cascade, antigen-antibody complexes

alternative pathway: C3 is cleaved, C3b accumulates on a microbe and acts as an opsonin to trigger the complement cascade, spontaneous C3 hydrolysis

lectin pathway: mannose (sugar found on many fungi, bacteria and viruses), binds to lectins and activates complement cascade, MBL-MASP complexes

Question 19

relationship between innate immune activation and fever

Answer 19

-inhibits growth of some microbes
-many enhance the activities of interferons, phagocytes, cells of specific immunity, and the process of tissue repair
-enhances innate immune activation

Question 20

process of fever

Answer 20

1. chemicals secreted by phagocytes travel in blood to hypothalamus
2. hypothalamus secretes prostaglandin, resetting hypothalamic thermostat
3. nerve impulses cause shivering, higher metabolic rate, inhibition of sweating, vasoconstriction
4. these processes increase body temperature to the point set by the hypothalamic thermostat

Question 21

role of dendritic cells in connecting innate and adaptive immunity

Answer 21

-link innate and acquired immunity
-professional Antigen presenting cells (APCs)… presents foreign antigen to T cells to induce acquired immune responses