IM processes

Question 1

What is the process of the type 1 interferon?

Answer 1

1. virus infected cell releases type 1 interferon into IF
2. most cells have receptors for type 1 interferon to bind
3. if non-infected cell, production of antiviral proteins will start
4. if cell later becomes virus infected, antiviral proteins will prevent viral replication

Question 2

what is the process of phagocytosis

Answer 2

Recognition: pathogen in extracellular fluid binds to cell membrane of phagocyte

Ingestion: pathogen enters phagocyte by phagocytosis and forms phagosome

Digestion: lysosome binds to phagosome to form larger phagolysosome (this means digestive components of lysosome in contact with pathogen)

Kill: pathogen now not functional so end products released either internally inside phagocyte or externally by exocytosis

Question 3

What is the process of the alternative complement pathway?

Answer 3

1. complement proteins (plasma proteins from liver) circulating as inactive in blood
2. inactive C3 binds to pathogen to activate
3. portion of active C3 called C3b left attached to pathogen
4. phagocyte has receptor for C3b so C3b is opsonin for phagocyte making for easier recognition and enhanced phagocytosis
5. other active C3b causes cascade of activations from C5-C9
6. activated C5-C9 inserted on pathogen cell membrane to form pore
7. pathogen intracellular environment now has fluid/material flowing into
8. this triggers apoptosis

Question 4

What is the process of inflammation?

Answer 4

Stage 1: release of inflammatory mediators
Stage 2: phagocyte movement into damage site from blood/neutrophils arrive early/monocytes maturing into wondering macrophages arrive later
-margination
-diapedesis
-chemotaxis
Stage 3: worn out, damaged, or dead cells replaced (may include angiogenesis)

Question 5

What is the process of antigen presentation - exogenous antigen?

Answer 5

1. phagocyte recognition and phagocytosis for antigen
2. antigen broken down and a piece combines with MHC class 2 into vesicle
3. vesicle moves to surface
4. exocytosis and antigen presentation on cell membrane surface
5. helper T cell with correct receptor can bind to antigen presentation for clonal selection

*macrophages, B cells, dendritic cells with MHC class 2 do exogenous antigen presentation for helper T cells

Question 6

What is the process of antigen presentation - endogenous antigen?

Answer 6

1. intracellular protein acts as antigen
2. viral protein broken down and a piece combines with MHC class 1 and forms vesicle
3. vesicle moves to surface
4. exocytosis and antigen presentation on cell membrane surface
5. cytotoxic T cell with correct receptor can bind to antigen presentation for clonal selection

*most body cells except RBC have MHC class 1 for endogenous antigen presentation to cytotoxic T cells