The Immune Response to Infectious Agents

Question 1

Humoral immunity is more important than cell-mediated immunity in controlling viral infections

Answer 1

false; cell-mediated is more important

Question 2

Deficiencies in these immune cells lead to chronic or recurrent viral infections

Answer 2

T cells; NK cells

note: persons with antibody deficiencies seldom suffer from more frequent viral infections than persons with normal immune systems

Question 3

In regards to innate immunity to viruses, what is the first line of defense against viruses and produced by infected cell within minutes of infection

Answer 3

IFN alpha and IFN beta

Question 4

Synthesis of IFN alpha and beta is induced by ____ of other microbial nucleic acids

Answer 4

dsRNA

Question 5

How does IFN alpha and beta protect neighboring cells from infection?

Answer 5

1. inhibits protein translation - by blocking elongation tf’s
2. destroys viral mRNA - oligoadenylate syntheses activates endonuclease
3. up-regulates class I MHC expression making it easier for Tc cells to “see” infected cells

Question 6

In regards to innate immunity to viruses, these cells kill virus-infected and neoplastic cells that have down-regulated class I MHC expression

Answer 6

NK cells

Question 7

NK cells use ___ ____ receptors to survey the surface of host cells for MHC molecules

Answer 7

killer inhibitory

Question 8

If no or too few class I MHC molecules are found by the KIR, the infected cell is ____ by the NK cell

Answer 8

killed

Question 9

NK cells participate in antibody-dependent cell-mediated cytotoxicity. They have ____ that binds to IgG Fc region coating the target cell and use perforin, granzymes, and FasL to kill targets by ____

Answer 9

CD16; apoptosis

Question 10

Like TH1 cells and Tc cells, NK cells produce ____, which is a weak anti-viral, up-regulates Class 1 and Class II MHC expression, and activates macrophages, Tc cells, and other NK cells

Answer 10

IFN gamma

Question 11

In regards to the adaptive immunity to viruses, phagocytes engulf virions and process the viral proteins and present them to TH cells. TH cells become activate through which receptor-ligand pairings

Answer 11

TCR - antigen
CD4 - class II MHC
CD40L - CD40
CD28 - B7

Question 12

Activated TH1 cells produce ____ and ___ which will act on NK cells and Tc cells to enhance their cytotoxicity for virus-infected cells

Answer 12

IL-2; IFN gamma

Question 13

IFN gamma will also stimulate B cells to secrete opsonizing classes of antibodies which facilitate removal of free visions by phagocytes that have ____ receptors

Answer 13

Fc gamma

Question 14

In regards to adaptive immunity to viruses, Tc cells are activated by CD8 - Class I MHC interactions. How are Tc cells further activated?

Answer 14

IFN gamma and IL-2

Question 15

Antibodies are most effective against ____ bacteria; CMI is most effective against ____ bacteria

Answer 15

extracellular; intracellular

Question 16

Otitis media would be a sign of what kind of deficiency?

Answer 16

antibody deficiency

Question 17

A deficiency in phagocytes would present as what?

Answer 17

skin infections, oral lesions, abscesses of organs, staph aureus

Question 18

Keratinized tissue, mucous, cilia, coughing, sneezing, urination, pH extremes, FAs, digestive enzymes, lysozymes are all examples of what part of innate immunity against bacteria?

Answer 18

physical and chemical barriers

Question 19

Prolonged antibiotic usage can lead to what?

Answer 19

C. Diff

Question 20

In regards to the adaptive immune response to bacteria, B-1 cells secrete ___ to T-independent antigens (encapsulated bacteria)

Answer 20

IgM

Question 21

In regards to the adaptive immune response to bacteria, antibodies limit bacterial motility by binding to ____ and limit bacterial attachment to host cells by binding to ___ and ____ molecules

Answer 21

flagellae; fimbriae; adhesion

Question 22

Fungal disease can result from either what two things?

Answer 22

lack of recognition of fungi; overactivation of inflammatory response

Question 23

Fungal disease is the most severe in hosts immunocompromised by what?

Answer 23

long-term corticosteroid use, leukemia or lymphoma, cancer chemo, immunosupression following transplant surgery

Question 24

Neutrophils, monocytes, and macrophages recognize fungi via receptors for _____, _____, and ____

Answer 24

mannan, glucan, and chitin

Question 25

In regards to the adaptive response to bacteria, what cells activate macrophages for protective CMI? What cells activate neutrophils?

Answer 25

TH1 cells; TH17 cells

Question 26

Pneumocytisis Jiroveci is ___ defining illness

Answer 26

AIDS note: due to T cell deficiency

Question 27

Extracellular protozoa are eliminated by antibody-mediated mechanisms. Antibodies opsonize protozoa for ____ or ADCC by ___ cells

Answer 27

phagocytosis; NK

Question 28

GI infection by ____ ____ is common in people with antibody deficiencies (Bruton's agammaglobulinemia)

Answer 28

Giardia lambila

Question 29

Intracellular protozoa are eliminated by cell-mediated immunity by TH1-derived cytokines. ____ activates macrophages to kill ingested protozoa. ____ activates Tc cells for elimination of infected host cells.

Answer 29

IFN gamma; IL-2

Question 30

____ and ____ induce IgE synthesis by B cells. ____ activates eosinophils

Answer 30

IL-4; IL-13; IL-5

Question 31

Mast cells produce histamine and slow-reacting substance of anaphylaxis composed of what?

Answer 31

leukotrienes B4, C4 and E4

Question 32

Eosinophils produce what substances that are toxic to the worm?

Answer 32

major basic protein; eosinophil peroxidase, cationic protein, and neurotoxin

Question 33

Mast cells and basophils attract eosinophil via ___ ___ factor

Answer 33

eosinophil chemotactic

Question 34

Neutrophils undergo frustrated phagocytosis. Why?

Answer 34

because worm is too large to be ingested

Question 35

In regards to evasion of the immune response by infectious agents, bacterial capsules are antiphagocytic. What are the capsules neutralized by?

Answer 35

antibody

Question 36

In regards to evasion of the immune response by infectious agents, ____ ____ allows the microbe to dodge the immune system by changing the antigens displayed on the microbe surface

Answer 36

antigenic variation

Question 37

In regards to the Influenza virus, this is caused by point mutations in the viral genome which result in minor antigenic changes to the viral hemagglutinin and/or neuraminidase molecules over time

Answer 37

antigenic drift

Question 38

In regards to the Influenza virus, this is a major, abrupt change in the hemagglutinin and/or neuraminidase molecules that results in reassortment of the segmented influenza genome when more than one viral subtype infect the same host cell

Answer 38

antigenic shift

Question 39

The result of antigenic drift and shift is that one influenza infection does not confer what?

Answer 39

protection against a subsequent infection

Question 40

In regards to evasion of the immune response by infectious agents, Strep pneumoniae has how many serotypes?

Answer 40

90; infection with one serotype does not confer protection against another

Question 41

Mycobacterium tuberculosis, Histoplasma Capsulatum, and Toxoplasma gone survive how?

Answer 41

intracellularly in phagocytes

Question 42

EBV encodes a protein similar to ____ that interferes with TH1 maturation and function

Answer 42

IL-10

Question 43

HIV kills ____ T cells

Answer 43

CD4+

Question 44

_____ _____ produces IgA proteases that destroy this immunoglobulin at mucosal surfaces

Answer 44

Neisseria gonorrhoeae

Question 45

Protein ___ from staph and protein ___ from strep block IgG Fc-mediated effector functions

Answer 45

A; G note: these proteins bind to the Fc fragment of IgG so that it cannot fix complement, interact with the Fc gamma receptors on phagocytes (they interfere with opsonization), or facilitate ADCC