physiology of normal white blood cells

Question 1

what are lymphocytes? 3

Answer 1

• majority of lymphocytes are B cells or T cells
• both B and T cells have antigen specific receptors
• 5% of lymphocytes are NK cells, and do not have antigen specific receptors

Question 2

what are basophils? 7

Answer 2

• lobed nuclei and heavily granulated cytoplasm
• non-phagocytic cells
• function by releasing pharmacologically active substances from their cytoplasmic granules
• circulate in the blood
• recruited to the site of allergic reactions or parasitic infections
• express FceRI which allow binding
• allergen can bind to allergen specific IgE bound to the cell surface of basophils causing degranulation of effector mediators

Question 3

what are eosinophils? 6

Answer 3

• have bilobed nuclei and granulated cytoplasm
• motile phagocytic cells that migrate from the blood into the tissues
• majority are located in tissues
• express FceRI upon activation
• granule containing toxin such as peroxidase
• attack parasites in the GI, respiratory and Genito-urinary tracts

Question 4

what are monocytes? 6

Answer 4

• kidney shaped nucleus
• resovoiur of monocytes in the spleen
• also circulate in the blood stream where they enlarge
• migrate to the tissues about 1 day after release from the bone marrow
• blood borne phagocytes
• precursors to macrophages

Question 5

what are macrophages? 5

Answer 5

• found in tissues
• 5-10 fold larger than monocytes
• contain more organelles compared to monocytes
• lifespan is months to years
• tissue resident in phagocytes

Question 6

what happens to blood cells during bacterial infection? 2

Answer 6

• increased neutrophils

- increased monocytes in chronic infection

Question 7

what happens to blood cells during viral infection? 2

Answer 7

• increased lymphocytes

- sometimes increased monocytes

Question 8

what happens to blood cells during parasite infection? 2

Answer 8

• increased eosinophils

- activation of mast cells

Question 9

what happens to blood cells during fungal infection?

Answer 9

increased monocytes

Question 10

what happens to blood cells during allergy? 3

Answer 10

• increased basophils
• increased eosinophils in chronic phase
• activation of mast cells

Question 11

describe the recruitment of leucocyte function? 2

Answer 11

• interaction of leucocytes with the blood vessels is key to this recruitment
• recruitment of leucocytes from the blood to the tissues is key to their immune functions

Question 12

what are cytokines? 5

Answer 12

• low molecular weight proteins or glycoproteins
• act as the messenger molecules of the immune system
• secreted primarily by the white blood cells
• also assist in regulating the development of immune effector cells
• generally act locally as paracrine signalling

Question 13

what is inflammation? 6

Answer 13

• a response of vascularised tissue to infections and damaged tissue
• heat
• redness
• pain
• swelling
• bring cells and molecules involved in host defect and repair to the site of infection

Question 14

what are the components of the inflammatory response? 3

Answer 14

• blood vessels
• phagocytic leucocytes
• plasma proteins

Question 15

give an overview of inflammation? 5

Answer 15

• blood vessels dilate
• blood vessels become more permeable
• circulating leucocytes migrate into the tissue
• leucocytes are activated
• activated leucocytes destroy microbes and unwanted material

Question 16

what is the difference between acute and chronic inflammation? 9

Answer 16

acute:

• initial rapid response
• develops within minutes
• lasts hours to days
• predominantly mediated by neutrophils
• resolves once stimulus is removed

chronic:

• lasts weeks to months
• predominantly mediated by mononuclear cells
• tissue destruction
• attempts at healing

Question 17

describe cell adhesion to the endothelium? 3

Answer 17

• initial contract= P-selectin and E-selectin expressed on activated endothelium is recognised by oligosaccharides on leucocytes
• tighter adhesion= intercellular adhesion molecules (ICAM) on the activated endothelium recognise the integrins on the leucocytes and bind to them
• adhering monocytes are stimulated by MCP-1 to cross the endothelium and lodge in the intima

Question 18

describe adhesion molecules? 3

Answer 18

• only present on activated endothelium
• the means that normal endothelium won’t recruit cells
• activated endothelium is an absolute requirement for inflammation

Question 19

describe the activation of recruited leucocytes? 3

Answer 19

• phagocytic cells can recognise, ingest and destroy many pathogens
• these cells recognise pathogens damaged host molecule by means of cell surface receptors that can discriminate between the surface molecules displayed by pathogens and host cells
• these receptors can also recognise damaged host molecules

Question 20

how can recognition lead to phagocytosis? 4

Answer 20

• macrophage mannose receptors: ligand= conserved carbohydrate structures
• scavenger receptors: ligand= anionic polymers, acetylated and oxidised LDL
• toll like receptors: ligand= range of ligands for various TLRs
• opsonisation of pathogens (coating with circulating pathogens) is also important

Question 21

what areas of pathogenesis does atherosclerosis involve? 3

Answer 21

• endothelial dysfunction
• inflammation
• dysregulation of lipid metabolism