Innate Immunity

Question 1

what are routes of entry for pathogens through mucosal surfaces?

Answer 1

• airway
• GI
  tract
• GU

Question 2

what are routes of entry for pathogens through external epithelia?

Answer 2

• external surface (skin)
• wounds and abrasions
• insect bites

Question 3

what pathogen causes meningococcal meningitis?

Answer 3

neisseria meningiditis

Question 4

what pathogen causes syphilis?

Answer 4

treponoma pallidum

Question 5

what pathogen causes athlete’s foot?

Answer 5

tinea pedis

Question 6

what are the phases of innate immunity?

Answer 6

• infection
• recognition by preformed nonspecific effectors
• removal of infectious agent
• 0-4 hours

Question 7

what are the phases of early induced response?

Answer 7

• infection
• recruitment of effector cells
• recognition and activation
• removal of infectious agent
• 4-96 hours

Question 8

what are the phases of adaptive immune response?

Answer 8

• infection
• transport of antigen to lymphoid organs
• recognition by naive B and T cells
• clonal expansion of effector cells
• removal of infectious agents
• > 96 hours

Question 9

what are some mechanical barriers to infection?

Answer 9

• tight junctions between cells
• air and fluid flow across epithelium
• movement of mucus by cilia

Question 10

what are some chemical barriers to infection?

Answer 10

• fatty acids on skin
• enzymes: lysozyme in saliva, swear and tears
• low pH in stomach
• antibacterial peptides: defensins (skin and gut), cryptidins (gut)

Question 11

what are some microbiological barriers to infection?

Answer 11

normal flora compete for nutrients and attachment (biofilms), and also produce antibacterial substances (colicins)

Question 12

what are monocytes?

Answer 12

• 1 of 3 types of phagocytic cell of immune system
• circulate in bloodstream
• differentiate into macrophages in tissue

Question 13

what is the role of a macrophage?

Answer 13

• phagocytosis and killing of microorganisms

- activation of T cells and initiation of immune response

Question 14

what are examples of granulocytes?

Answer 14

• neutrophils
• eosinophils
• basophils

Question 15

what is an alternate name for granulocytes?

Answer 15

polymorphonuclear (PMN) leucocytes - due to shape of nuclei

Question 16

what is the role of a neutrophil?

Answer 16

• phagocytosis and killing of microorganisms

- most numerous and important cell of innate immunity

Question 17

what does a deficiency of neutrophils lead to?

Answer 17

overwhelming bacterial infections

Question 18

what is the role of an eosinophil?

Answer 18

• killing of antibody-coated parasites through release of granule contents
• important in parasite defence

Question 19

what is the function of a mast cell?

Answer 19

• expulsion of parasites from body through release of granules containing histamine and other active agents
• well known due to IgE mediated triggering in allergies
• effect vascular systems

Question 20

what is the role of a basophil?

Answer 20

function similar and complementary to eosinophils and mast cells

Question 21

what are lymphocytes?

Answer 21

• B or T cells
• B cells produce antibody
• T cells becoming cytotoxic cells (CD8) or helper cells (CD4)

Question 22

what are natural killer (NK) cells?

Answer 22

• large granular lymphocytes

- can recognise virally infected cells non-specifically

Question 23

what are dendritic cells?

Answer 23

• potentially the most important immune cell
• bridges innate and adaptive immune responses
• specialised in antigen uptake and antigen presentation

Question 24

what is the difference between NK cells and T cells?

Answer 24

• NK cells are not antigen specific

- don’t undergo length clonal expansion of T cells in lymph nodes when virus detected

Question 25

what is the role of the complement cascade?

Answer 25

• part of immune system that enhances (complements) ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism
• promotes inflammation (heat labile component of plasma)
• attacks the pathogen’s plasma membrane

Question 26

what are the 3 activation pathways that trigger the complement cascade?

Answer 26

• classical
• lectin
• alternative

Question 27

what is the first phase of the classical pathway of the complement cascade?

Answer 27

antibody binds to specific antigen on pathogen surface

Question 28

what is the first phase of the lectin pathway of the complement cascade?

Answer 28

mannose-binding protein binds to pathogen surface

Question 29

what is the first phase of the alternate pathway of the complement cascade?

Answer 29

pathogen surface creates local environment conducive to complement activation

Question 30

what are the results of complement activation?

Answer 30

• recruitment of inflammatory cells
• opsonisation of pathogens, facilitating uptake and killing by phagocytic cells
• lysis and death of pathogens

Question 31

what is the classical pathway initiated by?

Answer 31

activation of C1 complex

Question 32

what is the lectin pathway activated by?

Answer 32

• MBL

- MASP-1 and 2

Question 33

what is the alternative pathway activated by?

Answer 33

spontaneous hydrolysis of serum C3