Kuby Chapters: Immunology

Question 1

How are the innate and adaptive immune systems different?

Answer 1

INNATE: built-in ability to detect and attack pathogens
- Response time: MINUTES / HOURS
- LIMITED SPECIFICITY & DIVERSITY
- MAKES COMPLEMENTS

ADAPTIVE: acquired ability to recognize and destroy pathogens
- Response time: DAYS
- HIGHLY SPECIFIC & DIVERSE
- MAKES ANTIGENS
* CREATES MEMORY

Question 2

What are the components of the innate immune system?

Answer 2

Phagocytes:
- monocytes
- macrophages
- neutrophils
- dendritic cells

Mast Cells

Natural Killer (NK) Cells

• Also includes the other natural defenses like skin, cilia/mucus in the respiratory tract, and digestive enzymes in the stomach.

Question 3

What are the components of the adaptive immune system?

Answer 3

B CELLS, T CELLS & ANTIGEN-PRESENTING CELLS (MHC)

• T lymphocytes in the tissue between the body’s cells. B lymphocytes, also found in the tissue between the body’s cells. Antibodies in the blood and other bodily fluids

Question 4

How is the innate immune system activated?

Answer 4

Innate: activated immediately upon detection of damage or infection

• Pattern recognition receptors (PRRs) on phagocytes recognize pathogen-associated molecular patterns (PAMPs) found on microbes and damage-associated molecular patterns (DAMPs) found on aging, dead, or damaged self structures. PRRs target them for destruction.

Question 5

How is the adaptive immune system activated?

Answer 5

Adaptive: responds after being presented with antigens obtained via the innate system

• When a B or T cell interacts with its specific antigen, it is selected and becomes activated

Question 6

What happens after the adaptive immune system is activated?

Answer 6

Proliferation: producing a large number of clones
Each clone is reactive against the antigen that initially stimulated the original lymphocyte

Question 7

What are Antigens?

Answer 7

ANTIGENS: Substances that react with antibodies on B Cells or T Cell Receptors.

• Individual B and T cells each have an individual specificity for a single antigen. This is due to each cell having many copies of a receptor on their surface that only bind to one type of antigen

Question 8

What are the anatomical barriers that aid the immune system?

Answer 8

SKIN and MUCOSA provide an effective immune barrier between the internal and external environment. Skin acts as not only a physical barrier but also a chemical shield.

Question 9

What are PAMPs?

Answer 9

Pathogen-Associated Molecular Patterns:
receptors found on unwelcome microbes

Question 10

What are DAMPs?

Answer 10

Damage-Associated Molecular Patterns:
infected cells send out signals to the immune system alerting it

Question 11

What are PRRs?

Answer 11

Pattern Recognition Receptors:
located on the macrophages to identify PAMPs

Question 12

What is a MAC?

Answer 12

Membrane Attack Complex:
comes from the complement system and punches a hole in bacteria to kill it through osmosis

Question 13

What is a Complement?

Answer 13

A series of proteins that will activate whenever a microbe comes in.

A cascade system that enhances antibodies and phagocytes.

Question 14

What is Inflammation? Describe the process of Inflammation.

Answer 14

• A non-specific reaction to noxious stimuli
• Mast cells release histamines, causing an increase in blood flow resulting in swelling and redness
• Cytokines are released increasing immune response.
• Pro-inflammatory cytokines and chemokines (Cell signaling molecules) are triggered by innate responses to infection, damage, or harmful substances –> Recruitment of neutrophils and other leukocytes from the blood to the site of damage/infection

Question 15

What are antibodies? How are they produced? What are their characteristics?

Answer 15

ANTIBODIES: blood proteins that control and stop antigens
- Secreted by B (plasma) Cells
- Characterized by heavy (stem) and light (arms) chains (Y!)
- Two binding sites allow antibodies to stop antigens in the blood stream

Question 16

What are immune cells? How are they produced?

Answer 16

Lymphocytes (T cells, B cells, and NK cells), neutrophils, and monocytes/ macrophages

• All cells of the immune system are CREATED IN BONE MARROW from a common type of starting cell, called a STEM CELL. These stem cells later develop into specific cell types, including red blood cells, platelets (important for blood clotting), and white blood cells (important for immune responses).

Question 17

What are the Primary and Secondary Lymphoid Organs?

Answer 17

PRIMARY LYMPHOID ORGANS: include the bone marrow and the thymus. They create special immune system cells called “Lymphocytes” (T CELLS & B CELLS)

SECONDARY LYMPHOID ORGANS: These organs include the lymph nodes, the spleen, the tonsils and certain tissue in various mucous membrane layers in the body. TRAP ANTIGEN

Question 18

Where do T Cells & B Cells go to mature?

Answer 18

T Cells: Thymus

B Cells: Secondary Lymphoid Organs

Question 19

What are T Cells? What are the different kinds of T Cells and what are their functions?

Answer 19

Helper T Cells (Th): stimulates B and T cell activity (with viral/microbial specific antigen)

Cytotoxic T Cells (Tc): kills infected cells

Question 20

What are Toll-like Receptors? What is their function?

Answer 20

A specific type of Pattern Recognition Receptors; membrane-bound on macrophages and dendritic cells; part of the innate immune system

They recognize microbes that are trying to gain access to the cell or damaged self-tissue and initiate the immune response and inflammation.

Question 21

What is the Thymus?

Answer 21

The organ primarily responsible for the production and maturation of immune cells (between lungs).

• Thymus produces mature T cells which upon reinfection will have many available T Cells

Question 22

What is the difference between a primary immune response and a secondary immune response (with memory)?

Answer 22

A primary immune response results in the generation of memory immune cells. A secondary immune response occurs as a result of a second exposure to an antigen. It is a much more rapid and sustained response due to the action of memory immune cells

Question 23

How is immunological memory achieved?

Answer 23

1. B Cells express a diversity of cell-surface antibodies
2. A foreign antigen interacts with one B Cell and that cell divides to form a population of clones
3. The B Cell clones differentiate into plasma cells that secrete antibodies AND memory cells with cell-surface antibodies

Question 24

How do pathogens evade the immune system? How do our cells recognize these pathogens?

Answer 24

One way in which an infectious agent can evade immune surveillance is by ALTERING ANTIGENS.

• Our cells recognize these pathogens with receptors that bind features of these regular patterns; these receptors are sometimes known as PATTERN-RECOGNITION RECEPTORS (PRRs)

Question 25

How do vaccines affect the immune system?

Answer 25

Vaccines introduce antigens into the body that imitate an infection and primes the immune system to respond

Question 26

What is used by the immune system to “track down” foreign molecules in the body?

Answer 26

Phagocytic cells such as dendritic cells, macrophages and B cells, which take up foreign antigens

Question 27

What is the process of Phagocytosis? What cells are involved?

Answer 27

Phagocytes engulfing pathogens:
Destruction occurs through enzyme degradation, antimicrobial proteins, and toxic effects of reactive oxygen and reactive nitrogen species (ROS and RNS)

• Cells Involved: Monocytes, Macrophages, Neutrophils, Dendritic Cells, and B Cells (kind of)

Question 28

What is Opsonin? What is Opsonization?

Answer 28

Opsonin: Complex molecules that attach themselves to pathogens and make it easier for macrophages and neutrophils to recognize and phagocytose that pathogen.

Opsonization: The innate immune system marking microbes for destruction using soluble Opsonin proteins

Question 29

How do our bodies respond to microbial invasion?

Answer 29

Antibodies attach to and immobilize microorganisms. They kill them outright or help neutrophils target and kill them. How well the immune system defends the body against each microorganism depends partly on a person’s genetic make-up.

Question 30

Which disorders can occur due to an immune system malfunction?

Answer 30

When your immune system fails to respond adequately to infection, it’s called an immunodeficiency, and you may be immunocompromised. People may also suffer from the opposite condition, an overactive immune system that attacks healthy cells as though they were foreign bodies, and that is called an autoimmune response.

Question 31

How do allergies occur?

Answer 31

Allergies occur when your immune system reacts to a foreign substance — such as pollen, bee venom or pet dander — or a food that doesn’t cause a reaction in most people.

Question 32

How are the cells in the immune system “called” to an infected location?

Answer 32

CHEMOTAXIS Chemical signals, such as CYTOKINES and chemokines, guide immune cells to the site of infection, where they can identify and eliminate pathogens.

Question 33

What is meant by “Humoral” Immunity?

Answer 33

Humoral immunity involves combating pathogens via antibodies, which are produced by B cells and can be found in bodily fluids. Antibodies can be transferred between individuals to provide passive immune protection.

Question 34

What does Antigen-Specific Immunity rely on?

Answer 34

Antigen-specific immunity relies on surface molecules, called B- and T-cell receptors, unique to each individual lymphocyte. These receptors bind to a specific pathogenic structure called an antigen.

Question 35

What is meant by “Clonal Selection”?

Answer 35

Clonal selection is the process by which individual T and B lymphocytes are engaged by antigen and cloned to create a population of antigen-reactive cells with identical antigen specificity.

Question 36

What are the 4 major categories of Pathogens?

Answer 36

Viruses
Bacteria
Fungi
Parasites

Question 37

How are specific T and B cells (that have been trained to fight a specific pathogen) in the Lymph Nodes notified so that they can come to the sight of infection?

Answer 37

DENDRITIC CELLS: Pick up antigens at the sight of invasion and display them on their cell surface as they travel to other parts of the body through the blood

Question 38

What do T Helper Cells do after being proliferated from CD4 cells?

Answer 38

EVERYTHING! haha. They present antigens and secrete cytokines that signal the creation of Cytotoxic T cells and the cloning of B Cells.

Question 39

What are Cytotoxic T cells responsible for?

Answer 39

Killing cells that have been infected by pathogens, such as virally infected cells.

Question 40

What are Plasma Cells?

Answer 40

B cells that have differentiated into antibody producing cells. Their job is to produce tons of antibodies that are specific to the invading pathogen.