Chapter 14

80) How do some pathogens prevent complement activation or avoid the effects of activated complement?

Some pathogens hijack the host's regulatory membrane proteins that inactivate C3b, preventing the triggering of the alternative activation pathway AND some pathogens produce C5a peptidase that destroys complement C5a, a chemoattractant that recruits phagocytes to the area of infection.

2) In which organism were phagocytes first reported?

Starfish larvae

75) Which of the following is mismatched regarding protection of the body from pathogens?

Stomach—acid conditions and normal microbiota

71) Please select the TRUE statement regarding Toll-like receptors (TLRs).

TLRs allow cells to detect patterns associated with microbes, indicating that the innate immune responses involve some specificity (although not the specificity of adaptive immunity).

48) Pattern recognition is involved in innate immunity.

TRUE

49) Defensins are short antimicrobial peptides found within mucous membranes and phagocytes.

TRUE

50) White blood cells also called leukocytes are important in immunity.

TRUE

52) Lymphocytes are the cells primarily responsible for the adaptive immune responses.

TRUE

53) All pathways of complement activation follow the same sequence after C3.

TRUE

4) Which is not involved in adaptive immunity?

Tear flow

76) Which of the following is NOT true of phagocytosis?

Within a phagolysosome, O2 consumption decreases dramatically, allowing an enzyme to produce reactive oxygen species (ROS), which are toxic.

64) A cell infected by viruses may die due to the actions of interferons. The same result would occur WITHOUT interferon—any cell infected by a virus would die directly from the virus. Is there any apparent benefit to the host organism from the interferon action?

Yes; when the interferon acts on a virally infected cell, it shuts down virus replication. Without interferon, the virus will eventually kill the cell, but only after it has replicated many times. IFNs may kill the host cell, but they will also prevent it from being used to replicate virus.

89) You tell your patient that tattoo ink can sometimes cause the skin reaction he is experiencing; red ink in particular can cause this because it commonly contains mercury and/or other heavy metals. Your patient has developed a granuloma at the site of his tattoo. When he asks you what a granuloma is, you tell him.

a collection of macrophages, giant cells, and T cells.

25) The complement pathway that is activated by binding of C3b to cell surfaces is the

alternate pathway.

92) Your patient questions why he has developed a granuloma. You explain to him that granulomas

are formed as an attempt by the body to wall off and contain persistent antigens - in his case, the red tattoo ink (red ink contains mercury compounds).

8) Normal microbiota

are the organisms that typically reside on and in your body AND protect against infection by pathogens.

91) Your patient wonders what giant cells are and how they form. You explain that giant cells.

are very large cells with multiple nuclei; they are formed by the fusion of many macrophages during a chronic inflammatory response.

12) In humans, the stem cells from which all blood cells arise are found in the

bone marrow.

20) Toll-like receptors

each recognize a specific "danger" molecule AND are embedded in cellular membranes.

39) Following digestion of a microorganism by phagocytes, the debris is excreted by

exocytosis.

45) Pyrogens are

fever-inducing substances.

44) One of the strongest indications of infectious disease is

fever.

13) All blood cells originate from the

hematopoietic stem cell.

33) The presence of long double-stranded RNA (> 30 bp)

induces synthesis of interferon.

27) C3a and C5a are involved in

inflammation AND attraction of phagocytes

41) The first host response to a nonspecific tissue injury is described as

inflammation.

47) Fever

inhibits bacterial growth AND speeds up the body's reactions.

10) Factors that work generically against any foreign substance entering the host are described as

innate immunity.

5) Skin and mucous membranes are mostly involved in

innate immunity.

31) The low molecular weight protein produced by animal cells in response to viral infections is

interferon.

24) The complement pathway that is activated by mannan-binding protein is the

lectin pathway.

11) The cells primarily involved in all immune responses are the

leukocytes.

18) The cells responsible for adaptive immunity are the

lymphocytes.

16) Allergic reactions mainly involve

mast cells.

29) The complex resulting from complement activity that leads to cell lysis is the

membrane attack complex.

42) The first kind of leukocyte lured to the site of inflammation is the

neutrophil.

7) Interferons, complement, lysozyme, and lactoferrin are all examples of

nonspecific antimicrobial factors.

28) C3b is involved in

opsonization.

38) The cellular organelle responsible for the digestion of ingested infectious agents is the

phagolysosome.

34) Interferons function to make cells

prevent viral replication.

32) Interleukins are

produced by leukocytes AND protein molecules.

46) During apoptosis, a cell will

self-destruct without causing an inflammatory response.

74) Which of the following is the correct sequence of events in the interferon response? 1. IFN induces synthesis of inactive antiviral proteins (iAVPs). 2. Virus enters host cell (cell 1) and replicates, producing long dsRNA. 3. Activated AVPs induce apoptosis of infected cell. 4. dsRNA induces synthesis and secretion of IFN to neighboring cells. 5. Entry of virus into cell armed with iAVPs (cell 2) activates these proteins.

2, 4, 1, 5, 3

66) Which of the following is a bacterial product?

Colicin

90) Your patient doesn't understand all of the cell names that you have used. You educate him on the role of each cell type. One cell type that plays a role in adaptive immunity rather than innate immunity. Which cell is this?

Dendritic cells—antigen-presenting cells that "show" antigens to T cells, playing an essential role in their activation.

86) Which of the following do you think would be a possible way to cure a person with LAD?

Giving the person a hematopoietic stem cell transplant—this would replace the person's defective leukocytes with healthy leukocytes.

30) Which of the following are most susceptible to complement lysis?

Gram-negative bacteria

72) Which of the following would NOT trigger an inflammatory response?

Induction of antiviral protein synthesis by IFNs.

68) Please identify the mismatched pair.

Peritoneal macrophages—meninges

67) Which of the following are enzymes found in neutrophil granules, saliva, and milk that react with hydrogen peroxide to form antimicrobial compounds?

Peroxidases

37) Which activity of the virally invaded cell triggers production of interferon?

Production of dsRNA

40) The four cardinal signs of inflammation are

Redness, heat, swelling, pain

78) Fever allows the body to fight microbial invaders by which of the following mechanisms?

Fever prevents microbes with lower optimum temperatures from growing, giving the immune system time to eliminate those cells.

77) Please select the correct sequence for the steps of phagocytosis: 1. Conditions in the phagosome change, increasing its antimicrobial activities. 2. The phagocytic cell binds microbial invaders and engulfs them, internalizing them in a phagosome. 3. Phagocytic cells are recruited to the site of an injury by chemoattractants. 4. Within the phagolysosome, various factors work together to destroy an engulfed invader. 5. The phagosome fuses with enzyme-filled lysosomes, forming a phagolysosome.

3, 2, 1, 5, 4

83) When microbes are introduced into normally sterile body sites, or when tissues are damaged, inflammation occurs. The purpose of this is to contain a site of damage, localize the response, eliminate the invader, and restore tissue function. Select the correct sequence of events for an inflammation response. 1. The phagocytes then produce other adhesion molecules that strengthen their attachment to the endothelial cells. 2. Tight junctions between endothelial cells are disrupted, allowing leakage from the vessels into the tissue. 3. Endothelial cells of the blood vessels produce adhesion molecules that loosely "grab" phagocytic cells. 4. In response to various chemoattractants, the phagocytes leave the blood vessels and move into the surrounding tissues. 5. The diameter of local blood vessels increases due to the action of inflammatory mediators, slowing blood flow in the area.

5, 2, 3, 1, 4

9) Iron

A) is required by microorganisms. B) binds to lactoferrin. C) is necessary for the functioning of some enzymes. D) binds to transferrin. E) All of the answer choices are correct.

85) Given the name "leukocyte adhesion deficiency," which of the following steps in the inflammation process given below do you think is/are not carried out in a person with this condition? 1. Tight junctions between endothelial cells are disrupted, allowing fluid to leak from the vessels into the tissue. 2. The phagocytes bind to the endothelial cells and exit the blood vessel by a process called diapedesis. 3. Once in the tissues, phagocytic cells engulf and destroy any microbial invaders. 4. The increase of fluids in the tissues causes the swelling and pain associated with inflammation. 5. The diameter of local blood vessels increases due to the action of inflammatory mediators.

Answer: 2. The phagocytes bind to the endothelial cells and exit the blood vessel by a process called diapedesis.

3) Which is not a component of innate immunity?

Antibody

70) Which of the following are lymphocytes?

B cells, T cells, AND NK cells

26) The key molecule upon which all complement pathways converge is ________.

C3

62) A physician is attempting new therapies for HIV patients who are suffering from an impaired immune response. He decides to try using a recombinant form of colony-stimulating factor cytokine (CSF). Why?

CSF will help to stimulate the production of new lymphocytes, the very cells that are affected by HIV. This may help to keep the patients' immune responses "normal" for a period of time.

88) You go on to explain to your patient that his skin and mucous membranes are protected from microbes by a number of antimicrobial substances. You inadvertently make a mistake during this explanation. Which of the following definitions is INCORRECT?

Defensins—short chains of carbohydrates that have strong antimicrobial properties.

58) What two functions do phagocytes serve in immune responses?

Engulfment/destruction of foreign cells AND alerting the other cells of the immune system to an invader

73) Which of the following is least likely to be detected by pattern recognition receptors?

Enzymes involved in glycolysis

51) Mast cells are only found in the blood.

FALSE

54) Gram-negative bacteria are less susceptible to complement lysis than Gram-positive bacteria.

FALSE

55) Interferon directly interacts with and destroys viruses.

FALSE

56) Neutrophils are the second phagocytic cell to respond to an infection.

FALSE

57) Fever often enhances bacterial survival during an infection.

FALSE

65) Please identify the INCORRECT definition regarding innate immunity.

Innate lymphoid cells—a group of lymphocytes that have increased specificity in their mechanism of antigen recognition (example: natural killer (NK) cells).

35) Which of the following cytokines is most antiviral in its action?

Interferon

36) Which of the following statements about interferon is incorrect?

It only works on a few specific types of virus.

60) Toll-like receptors (TLRs) bind molecules on pathogens. Why is this helpful to the immune response?

It provides a general response to broad categories of molecules/cells that should NOT be in our system, as we don't have these molecules on our own cells.

69) How are macrophages and neutrophils similar, and how are they different?

Macrophages and neutrophils are both phagocytic cells. Macrophages reside in the tissues while neutrophils typically circulate in the blood.

1) Phagocytes were first discovered and named by

Metchnikoff.

79) The body's own cells do not trigger the alternative pathway of complement system activation. Why is this?

Molecules in host cell membranes bind regulatory proteins that will inactivate any C3b molecules that attach to the membrane

17) Which of the following are referred to as mononuclear phagocytes?

Monocytes and macrophages

14) Which of the following are phagocytic cells found in the human body?

Neutrophils AND macrophages

61) Smoking impairs the ciliated cells of the middle portion of the respiratory tract. Many analgesic drugs (painkillers) impair peristalsis (the churning motion of the digestive tract). The result of either of these activities leads to an increased risk of infection in their respective areas. Why?

The actions of the cells in these areas help to propel pathogens out of the area, serving as a part of the physical barrier system. When they are impaired/slowed, bacteria and other pathogens have an easier time adhering to the tissues in the area and causing an infection.

63) Syphilis, an STI, was once treated by intentionally infecting the patient with the parasite that causes malaria, a disease characterized by repeated bouts of fever, shaking, and chills. Why might this treatment cure syphilis?

The effect of driving up the body temperature for periods of time can shut down the temperature-sensitive replication of the bacterium that causes syphilis. This gives the immune system time to eliminate it properly.

82) Which of the following is NOT true of neutrophils?

Their numbers significantly decrease during most bacterial infections.

81) Which of the following is NOT a leukocyte? A) B cell B) Basophil C) Macrophage D) Neutrophil

These are all leukocytes

21) Which statement about complement proteins is FALSE?

They are part of the specific immune defense system.

59) How do cytokines function?

They are secreted by one cell type, then bind to a receptor on target cell causing a signal within that cell that turns on (or off) certain genes to achieve a response.

6) Which statement about skin and mucous membranes is NOT correct?

They are the first line of adaptive immunity.

84) Given what you understand about inflammation, why do you think a person with LAD experiences neutrophilia (high numbers of neutrophils in the blood)?

When a person has an infection, their number of neutrophils increases. In a person with LAD, the neutrophils do not attach to endothelial cells, and thus cannot not leave the blood vessel to enter infected tissue. As a result, they accumulate in the blood.

43) The attraction of leukocytes to the area of inflammation is referred to as

chemotaxis

22) The complement pathway that requires antibodies to be activated is the

classical pathway.

23) A group of interacting serum proteins that provide a nonspecific defense mechanism is

complement.

19) The "voices" of a cell, which carry messages, are

cytokines.

Your first patient of the day is complaining of pain in the area of his new tattoo. When you examine the tattoo, you note that the area around it is firm, red, and swollen. There is no evidence of pus, and your patient has a normal pulse, and no fever. You tell your patient that you have seen this type of response to a tattoo before, and that it is called a granulomatous reaction. You give him more information on the condition. 87) You tell your patient that when he got his tattoo, his first line of defense of his innate immunity was breached because his skin was damaged by the process. He asks you to explain what is included in the first line of defense and you tell him

skin and mucous membranes.