Introduction to the Immune System

Question 1

What are the main functions of the immune system?

Answer 1

• Recognize/destroy pathogens
• Recognize/clear effete/damaged self components
• Initiate tissue/wound healing processes
• Exhibit “tolerance” to innocuous material including self

Question 2

What can the CBC, serum markers, and serum antibodies tell us about immunity?

Answer 2

The presence of a current or previous infection

Question 3

What are some ways that the immune system can be harnessed to help patients?

Answer 3

• Vaccines –> Prevent infection

- Cancer Immunotherapies –> Treat cancer

Question 4

What are some clinical issues that the immune system can cause in response to certain treatments?

Answer 4

• Reactions due to blood transfusions

- Graft vs Host or Host vs Graft diseases

Question 5

Immunodeficiency

Answer 5

Immune defects which result in susceptibility to recurrent infection

Can be congenital or acquired

Examples of causes: Malnutrition, chemotherapy, and HIV-AIDS

Question 6

Immune hypersensitivity

Answer 6

Excessive immune reaction that leads to tissue damage

Examples: Allergies, chronic infections, contact sensitivities

Question 7

Autoimmunity

Answer 7

Loss of tolerance leads to reaction against healthy self

Examples: Type 1 diabetes and rheumatoid arthritis

Question 8

Immune Malignancy

Answer 8

Cancers of the immune system

Examples: leukemias and lymphomas

Question 9

Innate Immunity (Basics)

Answer 9

• Provides immediate protection from infection
• Does not change in response to reinfection
• Initiates processes that lead to activation of adaptive immunity

Question 10

Adaptive/Acquired Immunity (Basics)

Answer 10

• Adapts to a variety of non-self components
• Responses upon reinfection are faster, better, and stronger
• Generates proteins and cells that enhance innate immune function

Question 11

Main components of blood

Answer 11

55% is plasma (93% of which is water and 7% are proteins by weight)

45% consists of cells, of which 1.6% are leukocytes

Question 12

Neutrophils

Answer 12

• Innate immune cells
• Makes up ~50% of circulating WBCs
• Migratory and phagocytic

Question 13

Which cells are granulocytes?

Answer 13

Basophils
Eosinophils
Neutrophil

Question 14

Mast Cellls

Answer 14

• Innate immune cells
• Resident in connective tissue (includes epithelial linings of the lung and GI tract)
• Upon activation –> Release inflammatory mediators from their intracellular granules

Question 15

Are lymphocytes part of the innate or adaptive immunity?

Answer 15

Cells of the adaptive immunity are known as lymphocytes, and include B-cells and T-Cells

Question 16

What are effector cells?

Answer 16

Activated lymphocytes (T-Cells and B-Cells)

Question 17

What are do activated B-Cells do?

Answer 17

Produce soluble anti-bodies

Question 18

What cells are a part of the adaptive immunity?

Answer 18

B-Cells and T-Cells

Question 19

What cells are part of the innate immunity?

Answer 19

Basophils
Eosinophils
Neutrophils

Macrophages
Natural killer cells
Mast cells
Dendritic cells

Question 20

Which WBCs are fully differentiated before leaving the bone marrow?

Answer 20

Basophils
Eosinophils
Neutrophils

Naive B Cells

Question 21

Which WBCs differentiate from blood precursors after they enter tissue?

Answer 21

Mast cells
Macrophages
Dendritic cells

Question 22

Where do immature T cells complete maturation?

Answer 22

In the thymus where they then become fully differentiated naive T cells before reentering the blood

Question 23

Are naive B and T cells activated?

Answer 23

No. While they are differentiated, they need to be activated before B-Cells –> Plasma Cells and T-Cells –> Effector T-Cells

Question 24

What do hematopoetic stem cells (HSC) first differentiate into?

Answer 24

HSC are pleuripotent and self-renewing cells that can differentiate into:

• Common lymphoid progenitor
• Myeloid progenitor
• Erythroid progenitor

Question 25

What can erythroid progenitor cells differentiate into?

Answer 25

Erythroblasts which ultimately become erythrocytes or Megakaryocytes which produce platelets

Question 26

What can myeloid progenitor cells differentiate into?

Answer 26

The granulocytes (Basophils, Eosinophils, or Neutrophils) or The tissue resident cells (Macrophages, mast cells, or dendritic cells)

Question 27

What do monocytes differentiate into?

Answer 27

Macrophages

Question 28

What line of cells do monocytes come from?

Answer 28

They come from the myeloid line and come from myeloid progenitor cells

Question 29

What can common lymphoid progenitor cells differentiate into?

Answer 29

B-Cells T-Cells NK-Cells

Question 30

How long does the adaptive immunity take to activate?

Answer 30

Days to weeks

Question 31

Antibody

Answer 31

- Extremely high binding specificity | - Can target anything (protein, carbohydrate, nucleic acid, small molecules, drugs, etc.)

Question 32

Antigen

Answer 32

Any molecule that a antibody (or T-cell receptor) binds to

Question 33

Epitope

Answer 33

The part of an antigen molecule to which an antibody attaches itself

Question 34

Plasma cell

Answer 34

Activated Naive B Cells that produce antibodies

Question 35

Memory B Cells

Answer 35

Some activated B Cells become long lived memory B cells that circulate in the body which upon re exposure to the same infection produce a much faster and more robust response

Question 36

Primary response

Answer 36

Adaptive immunity is activated for the first time

Question 37

Secondary response

Answer 37

Adaptive immunity has memory B cells for that infection and can thus respond more quickly and with a stronger response

Question 38

Memory T cell

Answer 38

A small portion of long-lived T cells (called memory T cells) remains for rapid response upon pathogen re-exposure

Question 39

Helper T cell

Answer 39

- Type of activated T cell - Interact with macrophages that have eaten a particular pathogen - Induce killing activities of these macrophages

Question 40

Cytotoxic T cell

Answer 40

- Type of activated T cell | - When engaging with the surface antigen of a viral infected cell --> kills infected cell

Question 41

Cell mediated immunity

Answer 41

Activities of effector T cells

Question 42

Humoral immunity

Answer 42

Activities of antibodies made by Plasma cells

Question 43

Tolerance

Answer 43

Adaptive immunity avoiding reacting to self cells