Part 4

Question 1

What does cellular immunity consist of?

Answer 1

T lymphocytes that direct adaptive immunity or attack cellular targets

Question 2

What are the two major populations of T cells based on glycoprotein surface receptors?

Answer 2

• CD4 (Helper T cells, Regulatory T cells)
• CD8 (Cytotoxic T cells)

Question 3

What do T cells respond to?

Answer 3

Processed fragments of antigens displayed on surfaces of cells

Question 4

What are the two types of MHC proteins?

Answer 4

• Class I MHC proteins
• Class II MHC proteins

Question 5

Where are Class I MHC proteins found?

Answer 5

On all nucleated cells except RBCs

Question 6

What do Class II MHC proteins display?

Answer 6

Antigens from APCs (dendritic cells, macrophages, B cells)

Question 7

What is the first step in T cell activation by APC?

Answer 7

Antigen binding

Question 8

What triggers the co-stimulation step in T cell activation?

Answer 8

Binding of co-stimulatory signal on APC when processing a foreign antigen

Question 9

What happens during clone formation of activated CD4 T cells?

Answer 9

They proliferate and become memory and effector cells

Question 10

What roles do Helper T (T_H) cells play?

Answer 10

• Activate both humoral and cellular arms of adaptive defense
• Secrete cytokines

Question 11

How do Helper T cells assist in B cell activation?

Answer 11

By releasing interleukins as co-stimulatory signals

Question 12

What do Cytotoxic T (T_C) cells target?

Answer 12

Infected and cancerous cells

Question 13

What is the role of Regulatory T (T_reg) cells?

Answer 13

Slow or stop immune response

Question 14

What is the first line of defense in the immune response?

Answer 14

Surface barriers like mucous membranes

Question 15

What do virus-infected cells release to warn nearby cells?

Answer 15

Interferon

Question 16

What is the function of phagocytes in innate internal defenses?

Answer 16

Engulf viruses and release inflammatory chemicals

Question 17

What enhances inflammation during the immune response?

Answer 17

Complement activation

Question 18

What is the role of NK cells?

Answer 18

Recognize and kill virus-infected cells

Question 19

What do antibodies do in humoral immunity?

Answer 19

Neutralize viruses and enhance phagocytosis

Question 20

What is the difference between humoral immunity and cellular immunity?

Answer 20

• Humoral immunity targets extracellular viruses
• Cellular immunity targets intracellular viruses

Question 21

What is a primary immune response?

Answer 21

The body’s defense against its first exposure to a pathogen

Question 22

What is an immunodeficiency?

Answer 22

Conditions that impair production or function of immune cells or molecules

Question 23

What are examples of congenital immunodeficiencies?

Answer 23

• Severe combined immunodeficiency (SCID) syndromes

Question 24

What is an example of an acquired immunodeficiency?

Answer 24

Acquired immune deficiency syndrome (AIDS)

Question 25

What characterizes autoimmune diseases?

Answer 25

Loss of ability to distinguish self from foreign antigens

Question 26

What is hypersensitivity in the immune response?

Answer 26

Immune system damages tissue while fighting off perceived harmless threats

Question 27

What are the classifications of hypersensitivities?

Answer 27

* Acute/Type 1/Immediate hypersensitivities * Subacute hypersensitivities * Delayed hypersensitivities

Question 28

What occurs during the second exposure in Acute/Type 1 hypersensitivities?

Answer 28

Release of histamine and other inflammatory chemicals

Question 29

What are cytotoxic (type II) reactions?

Answer 29

Antibodies bind antigens on specific cells, leading to phagocytosis

Question 30

What is an example of delayed hypersensitivity?

Answer 30

Allergic contact dermatitis

Question 31

What are haptens?

Answer 31

Agents that diffuse through the skin and attach to self proteins