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Final

IMM250H1 Study Guide - Final Guide: Polly Matzinger, Microorganism, Interferon


Department
Immunology
Course Code
IMM250H1
Professor
Dana Philpott
Study Guide
Final

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Lecture THREE: INNATE IMMUNITY
*innate: property of something or action that is essential and specific to that thing or action and is wholly independent of any other object, action, consequence;
inborn
innate immunity
Æconserved throughout evolution
Æin all multicellular organisms
Æorganisms possess a set number of recognition molecules
Æcells are immediately active
Æhas no memory
adaptive immunity
Ærelatively recent ± 500 million years ago
Æunique to vertebrates
Æinfinite number of recognition molecules/antibodies
(through the ability to mutate genes, we can have millions of combinations of
antibodies that are able to recognize millions of antigens)
Æcells require priming
Æprovides memory of infection
INNATE &ADAPTIVE IMMUNITY WORK TOGETHER IN CONTROLLING INFECTION
Type of Immunity
- Effect
no innate immunity
- infections cannot be controlled at all
(innate immunity is required to initiate adaptive immunity)
innate immunity, no adaptive immunity
- infection is controlled at some rate (by innate immunity) but microbial growth continues and
cannot be cleared
innate immunity + adaptive immunity
- infections are cleared (by innate and adaptive immunity)
HOW DO CELLS KNOW SOMETHING IS FOREIGN
Dr. Charles Janeway
Dr. Polly Matzinger
- recognition of exogenous (non-self) microbial products
::consider the splinter = covered with bacterial products which are brought
into our system which is what the innate system responds to
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::when a splinter occurs it causes a lot of damage to the cells in the
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immune responses
they are both right
innate immunity
Ædepends on the recognition of:
*MAMPs: microbial-associated molecular patterns, signatures of microbial infections as they are pieces of the microbe; represent structural components of
microorganisms unable to be modified
*DAMPs: danger-associated molecular patterns, danger signals released from dead or dying cells
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overview of the innate immune system
1) recognition of s MAMP or DAMP by a protein recognition molecule (PRM)
2) the PRM induces a signal transduction
3) signal transduction induces changes in the cell to initiate a defence
4) immune system responds to kill and remove microbes
gram staining
Æbacteria is differentiated into 2 groups based on their gram stain: positive and negative, which is due to the compositions of their cell walls
1) bacteria is fixed to a slide via heat
2) crystal violet stain turns bacteria purple
3) iodine treatment is done so it complexes with violet stain forming complexes
4) decolorization with use of alcohol to get rid of the stain from bacteria
5) counter colour stain with pink
6) gram positive = bacteria that retain the original violet stain; gram negative = bacteria that lost the original violet and took up the counter stain
gram positive bacteria
Æcell wall is made up of a thick layer of Peptidoglycan and teichoic acid provide rigidity to the cell-wall by attracting cations such as magnesium and sodium.
Ætogether with lipoids, teichoic acid forms lipoteichoic acids that are extensions and act to anchor the peptidoglycan layer to the plasma membrane
gram-negative bacteria
Æcell wall consists of 2 membranes: an inner and outer membrane, with a periplasmic space (in between the 2 membranes) filled with a thin layer of peptidoglycan
Æthe outer membrane contains lipopolysaccharide (LPS)/endotoxin extensions and porins that act like pores for particular molecules
Æthere are no techoic or lipotechoic acids present
*note: antibiotics often target the petidoglycan layer as they form holes in the layer to release bacterial contents
*note: bacteria can also have flagella, protein made of flagellin, which allows movement of bacteria
MAMPs
Æinclude genetic material of bacteria and viruses
Ætheir DNA (different from mammalian DNA) contains CpG sequences (cytosine and guanine repeats with a phosphate separation Cytosine Phosphate Guanine)
which are unique to microbes as in mammalian DNA they are suppressed or modified
::if mammals have such CpG patterns, they become methylated to allow for suppression
Æare also associated with fungi
::Zymosan = carbohydrate from yeast cell walls
::Beta-glucan = carbohydrate from fungi cell walls
Æsuch compounds are specific to fungi so our immune system has evolved for such recognitions
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