Immune System - Lecture 2 Part B

Question 1

What is Phagocytosis?

Answer 1

The process of ingesting and destroying a pathogen

Question 2

What are the main cells that perform Phagocytosis?

Answer 2

• Monocytes
• Macrophages
• Neutrophils
• Dendritic cells

Question 3

What are the two main ways that Phagocytosis can be stimulated?

Answer 3

• Phagocytes recognizes PAMPs from a pathogen

* Phagocyte has receptors for opsonized pathogens

Question 4

Which complement protein is an example of an Opsonin?

Answer 4

C3B

Question 5

What can function as Opsonins?

Answer 5

C3B

Question 6

What is the difference between Opsonin and PAMP activated Phagocytosis?

Answer 6

Opsonized pathogens have an enhanced internalization

Question 7

What is Phagocytosis used for besides being used to kill?

Answer 7

To clean the a site post-infection

Question 8

What do Phagocytes use to recognize a pathogen?

Answer 8

PAMPs or Opsonins

Question 9

What happens after a Phagocyte recognizes PAMPs or Opsonins?

Answer 9

The membrane of the phagocyte starts elongating and surrounding the microbe for the process of internalization forming a phagosome

Question 10

What occurs in Phagocytosis once a Phagosome is formed?

Answer 10

The phagosome fuses with lysosome forming a phagolysosome which destroys the pathogen

Question 11

What steps must be taken if a pathogen was phagocytized by an antigen presenting cell?

Answer 11

The phagocyte must present the antigen to T lymphocytes for adaptive immunity

Question 12

What does the processing of Antigen presentation on a phagocyte depend on?

Answer 12

Whether it is an intracellular or extracellular antigen

Question 13

What is the process for presenting extracellular antigens?

Answer 13

After being ingested in the cell, the cell produces MHC II which fuses with an endosome of phagolysosome which degrades the invariant chain and exposes the binding site to the foreign antigen which binds to it and then migrates to the surface of the cell

Question 14

What does the Invariant chain on an MHC molecule do?

Answer 14

Prevents it from binding to our own proteins

Question 15

What do antigens presented by MHC II molecules get recognized by?

Answer 15

CD4+ lymphocytes or T-helper cells, T-lymphocytes

Question 16

Once an antigen is presented by MHC II what can it go on to do?

Answer 16

Activate T lymphocytes

Question 17

What is the process for antigen presenting of intracellular pathogens?

Answer 17

The virus is already in the cell and during replication a viral coating will be released into the cytoplasm and is destroyed by the protease system. The foreign peptides created from this go to the endoplasmic reticulum where MHC I molecules are produced and bind to antigens to express it on the plasma membrane

Question 18

What are intracellular antigens expressed by?

Answer 18

MHC I

Question 19

What are extracellular antigens expressed by?

Answer 19

MHC II

Question 20

What are antigens presented by MHC I recognized by?

Answer 20

CD8+ lymphocytes or T-cytotoxic lymphocytes

Question 21

What does MHC stand for?

Answer 21

Major histocompatibility complex

Question 22

Which molecules present intracellular antigens?

Answer 22

MHC I molecules

Question 23

Which type of MHC molecules are responsible for regular surveillance of the cells and why?

Answer 23

MHC I because they are present in all nucleated cells

Question 24

How does MHC I act as a window to what is happening inside the cell?

Answer 24

An infected or tumor cell has reduced MHC I expression

Question 25

Which cells are the best to eliminate infected MHC I cells?

Answer 25

T-cytotoxic cells

Question 26

What cells are required for T-lymphocyte activation?

Answer 26

MHC II cells presenting antigens

Question 27

Which cells are the best for fighting extracellular antigens presented by MHC II?

Answer 27

CD4+ lymphocytes and helper-T cells

Question 28

How do we prevent an exacerbated reaction in adaptive immunity?

Answer 28

By requiring antigen presenting cells to activate T-lymphocytes

Question 29

How does the Complement system stimulate the adaptive immune response?

Answer 29

By stimulating phagocytosis through opsonins and by stimulating inflammation