Immune System 3 Part 1

Question 1

What is the Third Line of Defense in our Immune System?

Answer 1

• Specific / “lock and key”.
• 3rd line of defense.
• Slower response, ultimate defense

Question 2

How do Innate and Adaptive Immunity differ?

Answer 2

Innate Immunity: This is the first line of defense and is non-specific. It recognizes general patterns shared by a broad range of pathogens, such as bacteria or viruses.

Adaptive Immunity: This is more specific and can recognize particular antigens, which are unique molecules on the surface of pathogens.

Question 3

How do Innate and Adaptive Immunity Recognise/Reject what is self and what is foreign (non-self)?

Answer 3

Innate Immunity:
- doesn’t have ability to distinguish self from non-self in a specific way.
- recognizes general features of pathogens, treating them as foreign without specific targeting.

Adaptive Immunity
- has mechanisms to recognize self-antigens and learn not to attack the body’s own cells through a process called immune tolerance.
- recognizes and targets specific antigens, allowing for a highly targeted response against particular pathogens.

Question 4

How does Memory differ in Innate and Adaptive Immunity?

Answer 4

Innate Immunity:
- It doesn’t have a memory component. Each exposure to a pathogen is treated as a new encounter.
- The response is generally consistent and doesn’t change significantly upon repeated exposure.

Adaptive Immunity
- It has a memory component, meaning that it “remembers” previous encounters with pathogens.
- The response is faster, stronger, and more specific upon re-exposure to a pathogen due to the immunological memory.

Question 5

What is an Antigen?

Answer 5

any molecule that can trigger an adaptive immune response against itself or cell bearing it

Question 6

What often Recognizes Antigens?

Answer 6

“Recognition” often proteins on immune cell membrane surface

Lymphocytes are essential cells of adaptive system.

Question 7

Lymphocyte Development

Where are B cells formed?

Answer 7

Arise and mature in bone marrow.

Question 8

Lymphocyte Development

Where are T cells formed?
What do they become?

Answer 8

• Arise in bone marrow
• Migrate to thymus as immature T cells.
• Mature in thymus to Helper, Regulatory, and
  Cytotoxic T cells

Question 9

Where do B and T cells Migrate to once formed? What are they then classified as?

Answer 9

They Migrate to secondary lymphoid structures and form clonal populations

At this point they are naïve lymphocytes

Question 10

What are Naïve Lymphocytes?

Answer 10

B and T Cells that:
- are not yet exposed to antigen.
- Have one specific surface antigen receptor (multiple copies).
- Genetically developed.

Question 11

Image

Answer 11

Question 12

Lymphocyte Receptors

What are Immunoglobulins (Ig)?

Answer 12

Immunoglobulins (Ig), also known as antibodies, are proteins produced by the immune system in response to the presence of antigens

Question 13

What are the 2 Types of Immunoglobulins (Ig)?

Answer 13

• 2 types – B cell receptors and antibodies.
• Antigens are able to react with B cell receptors or antibodies as part of activation stage of B Cell Activation

Question 14

What is the Structure of an Immunoglobulin (Ig)?

Answer 14

Structure – 4 chains – 2 heavy / 2 light.

• Constant end with stem binding site (always same within an Ig class).
• Variable ends with 2 of same specific antigen binding sites (millions of different within an Ig class).

Question 15

What are the 5 classes of immunoglobulins (Ig)?

Answer 15

IgG – bacteria and virus, largest class.
IgA – sweat, saliva, breast milk, tears, mucus, gastrointestinal secretions.
IgM – bacteria and virus, appear 1st, short lived.
IgE – allergic responses, parasites.
IgD – B cell activation.

Question 16

What is a MHC Protein?

Answer 16

major histocompatibility protein

Question 17

Lymphocyte Receptors

What is a T cell receptor?
How can it be Activated?

Answer 17

The T cell receptor (TCR) is a protein on the surface of T cells that recognizes antigens. For activation, the antigen must be presented in combination with major histocompatibility complex (MHC) proteins.

Question 18

What type of MHC do all humans share?

Answer 18

NONE!
Each individual has a unique set of MHC proteins on their cell membranes. MHC proteins act as “identity tags” or genetic markers of self. Only identical twins share the same MHC profile.

Question 19

What type of MHC do most cells have?
Which Cells don’t have it?

Answer 19

MHC class I are found on most cells Erythrocytes (RBC) do not have them

Question 20

Which T Cell recognizes antigens presented with MHC class I?

Answer 20

Cytotoxic T cells recognize antigens presented with MHC class I. These cells are important for killing infected or abnormal cells.

Question 21

Where is MHC Class II mainly found?

Answer 21

mainly on macrophages, B cells.

Question 22

Which T Cell recognizes antigens presented with MHC class II?

Answer 22

Helper T cells recognize antigens presented with MHC class II. They play a central role in coordinating immune responses, activating other immune cells, including B cells and cytotoxic T cells.

Question 23

What class are most Regulatory T cells involved in?

Answer 23

Most Regulatory T cells involve antigen presented with class II, small number with class I.

Question 24

MHC Proteins and NK Cells:

Answer 24

MHC proteins not required for NK cells – more non-specific binding like innate.