physiology of normal white blood cells Flashcards
what are lymphocytes? 3
- 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
what are basophils? 7
- 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
what are eosinophils? 6
- 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
what are monocytes? 6
- 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
what are macrophages? 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
what happens to blood cells during bacterial infection? 2
- increased neutrophils
- increased monocytes in chronic infection
what happens to blood cells during viral infection? 2
- increased lymphocytes
- sometimes increased monocytes
what happens to blood cells during parasite infection? 2
- increased eosinophils
- activation of mast cells
what happens to blood cells during fungal infection?
increased monocytes
what happens to blood cells during allergy? 3
- increased basophils
- increased eosinophils in chronic phase
- activation of mast cells
describe the recruitment of leucocyte function? 2
- 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
what are cytokines? 5
- 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
what is inflammation? 6
- 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
what are the components of the inflammatory response? 3
- blood vessels
- phagocytic leucocytes
- plasma proteins
give an overview of inflammation? 5
- blood vessels dilate
- blood vessels become more permeable
- circulating leucocytes migrate into the tissue
- leucocytes are activated
- activated leucocytes destroy microbes and unwanted material
what is the difference between acute and chronic inflammation? 9
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
describe cell adhesion to the endothelium? 3
- 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
describe adhesion molecules? 3
- only present on activated endothelium
- the means that normal endothelium won’t recruit cells
- activated endothelium is an absolute requirement for inflammation
describe the activation of recruited leucocytes? 3
- 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
how can recognition lead to phagocytosis? 4
- 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
what areas of pathogenesis does atherosclerosis involve? 3
- endothelial dysfunction
- inflammation
- dysregulation of lipid metabolism
