Innate Immunity

Question 1

Leukocytes

Answer 1

• innate and adaptive immune responses
• pluripotent hematopoietic stem cells
• common myeloid progenitor
• precursor from which macrohages, granulocytes, mast cells and dendrite cells of the innate immune system derive

Question 2

Macrophages

Answer 2

• also known as mature monocytes
• one of the three types of phagocytes
• found in nearly all tissues of the body
• longe-lived
• several functions: phagocytosis, secretion of pro-inflammatory cytokines, and chemotaxis

Question 3

Granulocytes

Answer 3

• neutrophils, eosinophils, basophils
• relatively short lived
• produced in vast quantities during immune responses

Question 4

Phagocytic neutrophils

Answer 4

• one of the most critical cells in innate immune responses
• wide variety of microorganisms they can phagocytise and destroy using degenerative enzymes within intracellular vesicles

Question 5

Eosinophils and basophils

Answer 5

• typically less abundant during a response
• contain a variety of enzymes and toxic proteins
• important primarily in the defense against parasites due to size
• play a roles in allergic inflammatory reactions
• more damaging than protective

Question 6

Dendritic cells

Answer 6

• 3rd type of phagocytic cell
• migrates through bloodstream and into tissues where they phagocytise particulate matter
• able to ingest large quantities of extracellular fluid (macropinocytosis)
• primary role: phagocytise pathogens, degrade them into basic fragments, and present fragments on their cell surface for recognition by a particular class of lymphocyte

Question 7

Cytokines

Answer 7

General term for any protein secreted from a cell that is capable of altering the behaviour of a cell bearing an appropriate receptor

Question 8

Chemokines

Answer 8

Secreted proteins that act as a chemo attractant to recruit neutrophils and monocytes from the bloodstream to the site of infection

Question 9

Acute inflammation

Answer 9

*Heat, pain, redness and swelling - effects of cytokines on local blood vessels
*Initiation: pathogens present within the body and produce compounds that are damaging to host tissues
:macrophages engulfs pathogens and secrete chemokines (vasoactive factors such as leukotrines, platelet-activating factors, prostaglandins = increases blood volume and capillary permeability)
:cytokines (interleukin-1 and tumour necrosis factor alpha) stimulates expression of adhesion molecules (selectins) on endothelial cells and adhere to neutrophils in the bloodstream as they pass by
:causes interaction with chemokines causing them to display integrity adhesion molecules on their surfaces
:results in extravastionof neutrophil through the endothelial wall into tissues where they aid marcophages in attacking pathogens
: damaged tissues releases bradykinin
-losses tight junctions between endothelial cells to promote extravasion
-interacts with local mast cells causing calcium influx that promotes their degranulation = causes histamine release and losses tight junctions further