Immunology Flashcards
1
Q
Compare innate and adaptive immune system?
A
Innate=
- Much earlier development evolutionary
- everyones is the exact same
- quick to react
Adaptive=
- very specific response
- slower than innate
- Has a memory is can give immunity
- changes over time
2
Q
What is the classical pathway of activating the complement system?
A
- Microbe is bound to the antibodies (bacteria bound to antibody)
- c1q proteins can detect the binding of the antibodies to the microbe
- the c1q will then bind to the antibody:microbe complex and this causes c1q to become activated
- once c1q is activated, it cleaves c4 into c4a and c4b
- c4b will bind to the microbe itself
- c2 will bind to c4b
- the activated c1q cleaves off c2 into c2a and c2b
- c2b remains stacked to c4b and forms an enzyme called the c3 convertase (c4bc2b)
- c3 converts cleaves c3 into c3a and c3b which have3 effector actions
- c3a is a small inflammatory peptide that leads to inflammation.
- c3b binds itself to the cell surface of the microbes which is helpful as it aids the macrophages to easily identify and eat the bacteria- acts as a tag.
- c3b will also bind to c5 allowing c3 converts to cleave c5 into c5a and c5b.
- c5a is also an inflammatory peptide that leads to inflammation
- c5b recruits c6, c7 and c8 and binds to the bacterial membrane surface
- between 8-16, c9 protein come and bind to the complex to form a pore in the bacterial membrane.
- if enough holes are created the contents will leak out- membrane attack complex (MAC)
3
Q
What is the lectin pathway of activating the compliment system?
A
- Mannose-binding lectin (MBL) is a protein that can identify the mannose sugar on bacteria as mannose is only found in bacteria and not human cells. therefore if mannose is present, bacteria is present.
- mannose-binding lectin binds to mannose
- mannose binding protein associate serine protease 2 (MASP-2) cleaves c4 into c4a and c4b
- c2 binds to c4b
- MASP-2 will then cleave the c2 bound to c4b into c2a and c2b
- c4b and c2b together form the enzyme c3 convertase
- c3 convertase cleaves c3 into c3a and c3b
- c3a is a small inflammatory peptide that leads to inflammation.
- c3b binds itself to the cell surface of the microbes which is helpful as it aids the macrophages to easily identify and eat the bacteria- acts as a tag.
- c3b will also bind to c5 allowing c3 converts to cleave c5 into c5a and c5b.
- c5a is also an inflammatory peptide that leads to inflammation
- c5b recruits c6, c7 and c8 and binds to the bacterial membrane surface
- between 8-16, c9 protein come and bind to the complex to form a pore in the bacterial membrane.
- if enough holes are created the contents will leak out- membrane attack complex (MAC)
4
Q
What are the symptoms of inflammation?
A
- rubor- redness
- dolour- pain
- calor- heat and fever
- tumour- swelling
- loss of function
5
Q
What happens to leukocytes in the bloodstream?
A
- They become attached to the chemotractins which flows the flowing of the leukocytes.
- they have then been captured and roll slowly until they become adhered to the endothelial cell layer
- they are then pushed through small groups in the endothelial layer (transmigration) and migrate into the tissue.
- this leads to swelling and release of prostaglandins causing pain
6
Q
What are the three stages of inflammation?
A
- 1st stage: Vasodilation= Mast cells or macrophages that detect the presence of bacteria release histamine, kinin, prostaglandin and leukotrienes
- The release of histamine leads to vasodilation- the blood vessels dilate, more blood rushes to the site of inflammation bringing more cells to the site swell hence redness and swelling.
-these cells migrate (via chemotaxis) and marinate into the tissue - diapedesis occurs- phagocytes force between the endothelium cells of the blood vessels and migrate into the tissue
- 2nd stage= once the phagocytes (neutrophils and macrophages) are migrating into the tissue, they will destroy the micro-organisms and any myuated o dead cells via phagocytosis
- 3rd stage: tissue repair- dead and damaged cells are rebuilt and replaced.
7
Q
Describe the process of phagocytosis:
A
- Plasma membrane engulfs the microbe and brings it inside the phagocyte in a phagosome ( a phagocytic vesicle)
- digestive enzymes are in the cell in vesicles called lysosomes
- lysosomes fuse with the phagosome to form a phagolysosome
- these enzymes digest the bacteria/microbe b
8
Q
What do we have on all of our cells that infected cells don’t?
A
MHC-class 1 protein is found in all human cells except RBC.
These virally infected cells don’t have MHC-class1 proteins own the cell surface so inhibitory receptors of the natural killer cell cant bind to them and be engaged so the NK cell will kill it.
9
Q
What its humoral immunity?
A
- Immunity driven by b-cells
- b-cells produce and release antibodies which neutralise extracellular microbes and ensure they are identified and killed.
10
Q
What is cell-mediated immunity?
A
- Driven by t-cells
- Helper t-cells release cytokines to activate macrophages to kill off microbes (helper t-cells ant kill themselves they activate other cells to )
11
Q
What is the purpose of the MHC class 1 protein?
A
- found on every body cell except RBC- acts as a marker for ourselves to tell us that the cell belongs to out body.
- They also find antigens and present them towards the. cell surface of t-cells. t-cells can only bind to an antigen if presented by a MHC
12
Q
What cells do MHC class 1 proteins interact with?
A
CD8 + positive t-cells
13
Q
What cells do MHC class 2 proteins interact with?
A
CD4+ Positive t-cells
14
Q
Describe the MHC class 2 pathway…
A
- If an antigen is taken up by endocytosis into a cell, it will be enclosed in a endocytic vesicle
- The vesicle enters the cell and the antigen will be broken down into different proteins
- MHC class 2 complexes are produced in the endoplasmic reticulum in the cell which are released in a vesicle also
- the two vesicles fuse and the protein will bind to the MHC complex and is transported to the cell surface ready to engage with a cd4+ t-cell.
15
Q
Describe the MHC class 1 pathway…
A
- occurs when a microbe is infecting the cell
- the microbe is not inside a vesicle this time
- microbial proteins are made inside the cells cytoplasm
- MHC class 1 complexes are produced in the endoplasmic reticulum
- MHC class 1 will bind some of the free proteins and a MHC:protein complex is made and transported to the cell surface and presents itself to CD8+ t-cells
