Deck 12: Host Defenses I: Overview and Nonspecific Defenses

Question 1

C A S E F I L E

Immune Trade-Off
I was working in a cardiologist's office when I met Mr. Campbell, a 65-year-old patient who had had a heart transplant three years previously following a viral illness that had damaged his heart irreparably. Mr. Campbell had done very well following his transplant and was a model patient. He never complained about the handfuls of drugs he had to take in order to suppress his immune system to prevent organ rejection. Everyone in the clinic looked forward to Mr. Campbell's office visits. His joy in his renewed health was infectious. He always had a huge smile and a joke to share with us.
Mr. Campbell came in one November morning 3 weeks earlier than his usual standing appointment. Although he smiled and joked, it was easy to tell that he was not feeling well. He told the doctor and me that he had been feeling weak and tired and had been experiencing a low-grade fever off and on for a couple of weeks. He was presently taking antibiotics for a chest infection. His family doctor had urged him to visit us sooner rather than later, concerned about his infection when Mr. Campbell was taking immunosuppressant drugs.
We took Mr. Campbell into an examining room. His vital signs were normal except for a moderate fever and a slightly elevated heart rate. He had a productive cough and his lungs sounded congested. He looked very pale. The doctor began to examine Mr. Campbell and discovered that he had several enlarged lymph nodes in his neck. Mr. Campbell admitted that his appetite had been "off" and he had lost some weight.
The doctor ordered a battery of tests: blood work, including a complete blood count, a chest X ray and an abdominal CT scan, in addition to his normal cardiac function tests. The results were worrisome. Mr. Campbell was anemic and his platelets were low. His white blood cells were abnormally low. More devastating was a tumor that was discovered during the abdominal CT scan. Mr. Campbell was scheduled immediately for biopsy of his swollen lymph nodes. The results were as we feared: Mr. Campbell was diagnosed with diffuse large B-cell lymphoma.
• What factor put Mr. Campbell at increased risk of developing lymphoma?
• Why is infection common in lymphoma?

Answer 1

Mr. Campbell underwent heart transplant following which he was prescribed drugs to suppress his immune system in order to prevent organ rejection. These immunosuppressant drugs in addition to his older age put Mr. Campbell at increased risk of developing lymphoma.
Lymphoma occurs commonly in immunocompromised individuals. Since the host immunity system is compromised the infections caused by viruses and bacteria are common in lymphoma. Malnutrition is also another cause of infections in lymphoma.

Question 2

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles and, in most cases, they do not have a single correct answer.
Suggest some reasons for so much redundancy of action and so many interacting aspects of immune responses.

Answer 2

There are reasons for the redundancy of action and so many interacting aspects of the immune response. Our immune system protects us and if it was to fail we could die from a common infection. Take for example a patient with no immune system. They have to live in a clean room and cannot interact with other. If they were to come out of the clean room they would die within days. If a patient with an immune system has an infection but the immune system misses it, it would be as if the patient had no immune system at all. Another reason for the many aspects of the immune response is that resistance can occur in the infectious agent but the agent is unlikely to be resistance to all the aspects of the immune reposes.

Question 3

Summarize the three lines of host defenses.

Answer 3

The host defense mechanism works at multilevel network of innate, nonspecific protections and specific immunities which are referred to as the first, second, and the third lines of defense.
• The first line of defense: The first line of defense provides protection against the oncoming pathogen by creating various barriers to restrict the entry of the pathogen into the body. The human body has several first line defense mechanism to encounter the pathogen entry. The intestinal microbiota serves as first line of defense. The skin and mucous membrane restrict the entry of the foreign particles. The tears and mucus also serve as first line of defense. The changes certain conditions like body temperature, pH and oxygen level, the entry to the pathogen gets restricted.
• Second line of defense: When the first line of defense fails, the immunity system launches its second line of defense to encounter the pathogen. It is cellular and chemical system that comes immediately to play if infectious agents make it past the surface defenses. Following are the various second line of defense mechanisms adapted by the immune system: fever, inflammation, mucus, phagocytes and antimicrobial proteins. These options serve to recognize and destroy the pathogen before it can inflict disease.
• Third line of defense: The third line of defense arises when both first and second line of defenses fail. It is acquired and specific immunity. Third line of defense includes specific host defenses that must be developed uniquely for each microbe through the action of specialized white blood cells.

Question 4

Select the correct answer from the answers provided. An example of a nonspecific chemical barrier to infection is

A) unbroken skin.
B) lysozyme in saliva.
C) cilia in respiratory tract.
D) all of these

Question 5

The presence of intestinal microbiota is considered
a. a first line of defense.
b. a second line of defense.
c. a third line of defense.
d. none of the above.

Question 6

This question connects previous images to a new concept.
From chapter 11, figure 11.3. Relate specific events in inflammation to the symptoms of pneumonia pictured in this drawing.
Reference: chapter 11, figure 11.3

Question 7

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles and, in most cases, they do not have a single correct answer.
a. Describe the main elements of the process through which the immune system distinguishes self from nonself.
b. How is surveillance of the tissues carried out?
c. What is responsible for this surveillance?
d. What does the term foreign mean in reference to the immune system?

Question 8

Identify three components of the first line of defense.

Question 9

Select the correct answer from the answers provided. Host defenses include both innate, nonspecific components and acquired specific components. Which of the following is/are exclusive to the acquired, specific defenses?

A) leukocytes
B) antimicrobial proteins
C) inflammation
D) fever
E) lymphocytes

Question 10

Which component(s) is /are associated with the second line of defense? Select all that apply.
a. maternal antibodies
b. chemical and physical barriers
c. fever and inflammation
d. interferons
e. phagocytosis

Question 11

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles and, in most cases, they do not have a single correct answer.
A cut in the skin breaches the first level of host defense. However, explain how a fully functioning first level may help reduce the negative effect of a cut.

Question 12

Describe two examples of how the normal microbiota contribute to the first line of defense.

Question 13

Select the correct answer from the answers provided. What is included in GALT?

A) thymus
B) Peyer's patches
C) tonsils
D) breast lymph nodes

Question 14

Which of the following act/acts as a filter for blood, removing worn-out red cells from circulation?
a. Peyer's patches
b. thymus
c. spleen
d. tonsils

Question 15

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles and, in most cases, they do not have a single correct answer.
In what ways is a phagocyte a tiny container of disinfectants?

Question 16

Define marker, and discuss its importance in the second and third lines of defense.

Question 17

Select the correct answer from the answers provided. Which of the following is a specialized tissue cell similar to basophils that triggers local inflammatory reactions and is responsible for many allergic symptoms?

A) mast cell
B) macrophage
C) dendritic cell
D) natural killer cell
E) neutrophil

Question 18

In order to assess immune function, the nurse anticipates that the physician will first order a
a. white blood cell (WBC) count with differential.
b. red blood cell (RBC) count with differential.
c. chemistry profile.
d. coagulation profile.

Question 19

Critical thinking is the ability to reason and solve problems using facts and concepts. These questions can be approached from a number of angles and, in most cases, they do not have a single correct answer.
One beautiful warm day in June, you are on a picnic and are stung on your finger by a bee. Although it hurt a little, you are soon enjoying the early summer day. The next morning you wake up to find that your finger is swollen, quite stiff, red, and warmer than the rest of your fingers. In addition, you seem to have a bit of a fever.
a. Which parts of the immune system seem to be activated?
b. Which classic responses to injury did you experience?
c. Explain which cytokines and cell types were probably most responsible for many of your symptoms.

Question 20

Name four body compartments that participate in immunity.

Question 21

Select the correct answer from the answers provided. An example of an exogenous pyrogen is

A) interleukin-1.
B) complement.
C) interferon.
D) endotoxin.

Question 22

During phagocytosis, which action is associated with destruction?
a. exocytosis
b. adhesion
c. oxidative burst
d. chemotaxis

Question 23

Connect the mononuclear phagocyte system to the rest of innate immunity.

Question 24

Select the correct answer from the answers provided. Which of the following components has a role in the third line of defense as well as in the second line of defense?

A) fever
B) complement
C) lysosome
D) all of the above

Question 25

Describe the structure and function of the lymphatic system.

Question 26

Select the correct answer from the answers provided. Which of the following substances is/are not produced by phagocytes to destroy engulfed microorganisms?

A) hydroxyl radicals
B) superoxide anion
C) hydrogen peroxide
D) bradykinin

Question 27

Name three kinds of blood cells that function in nonspecific immunity and the most important function of each.

Question 28

Select the correct answer from the answers provided. Which of the following is the end product of the complement system?

A) properdin
B) cascade reaction
C) membrane attack complex
D) complement factor C9

Question 29

Name two kinds of lymphocytes involved in specific immunity.

Question 30

List the four major categories of nonspecific immunity.

Question 31

Outline the steps in phagocytosis.

Question 32

Outline the steps in inflammation.

Question 33

Discuss the mechanism of fever and how it helps defend the body.

Question 34

Name three types of antimicrobial proteins.

Question 35

Compose one good overview sentence about the purpose and the mode of action of the complement system.