Lecture 3 Granulocytes Flashcards
What are Hematopoietic stem cells (HSCs)
HSCs have the ability to differentiate into many blood cells (red or white) through hematopoiesis
Where does hematopoiesis occur and what are the two major types of cells HSCs turn into
Occurs in the bone marrow
Two major types of cells:
Myeloid progenitor cells
Lymphoid progenitor cells
Order the total leukocytes in order of frequency in blood (7)
- Neutrophil (50-70%)
- Lymphocytes (20-40%)
- T - lymphocytes (7-24%)
- Monocyte (2-12%)
- (B Lymphocytes (1-10%)
6 Eosinophil (1-3%) - Basophil and mast cell (>1%)
What are the three types of granulocytes and their main function
Neutrophils - attack pathogens
Basophils/mast cells - inflammation/allergies
Eosinophils - antiviral/antiparasitic activity
What is the structure, major function and additional killing mechanism of Neutrophils
Structure - U shaped nucleus and possess granules containing bioactive compounds that assist in the destruction of microorganisms
Major function - Capture and destroy microorganisms within vacuoles
Additional killing mechanism - Extracellular traps (NETs) released from neutrophils catch and kill microbes
What are the four stages of phagocytosis
Chemotaxis - foreign substance releases chemotaxis attracting neutrophils
Adherence - foreign molecule adheres to neutrophil
Ingestion - molecule ingested
Destruction - destroyed in neutrophil due to reactive oxidative compounds
What is opsonization?
Bacteria are not easily captured because of their surface charge, bacteria coated by antibodies and/or complement bind to neutrophil receptors and are readily ingested, this is called opsonization
What are the three neutrophil receptors?
Cell adhesion molecules
Antibody receptors
Complement receptors
What is the structure, major function and how they are involved in type I hypersensitivity reactions of Eosinophils
Structure - possess granules containing bioactive and toxic compounds that assists in control of parasites and destruction of microorganisms
Major function - Destruction of parasitic helminths and phagocytosis and destruction of microorganisms
Involvement in type 1 hypersensitivity reaction - releases granules by exocytosis or piecemeal granulation
How do eosinophils attack helminths
Use oxidants, lipases and four major proteins:
Major basic protein
Eosinophil cationic protein
Eosinophil neurotoxin
Eosinophil peroxidase
IgE binds to eosinophils which helps kill the worms
What is the structure, function and possible role of Basophils
Structure - possess granules containing vasoactive molecules (similar to mast cells)
Function - unclear maybe inflammatory and allergic reactions
Possible role - modifying activity of T and B cells
Basophils are non-phagocytic cells
Describe Mast cells
Live in tissues, have granules. Important sensory and regulatory cells of innate and acquired immune systems. Also have a central role in type I hypersensitivity reactions
Describe Platelets
Small granulated anucleate blood cells. Critical role in blood clotting and important mediators of inflammation. Interact with other immune cells to facilitate effective immune responses
What are the 7 contents of neutrophil granules and their function
Lysozome - bactericidal
Defensins - bactericidal
Lactoferrin - Binds iron
Collagnese - degrades bacteria and tissue
Gelatinase - ‘’ ‘’ ‘’ ‘’ ‘’ ‘’
Myeloperoxidase - respiratory burst
Elastase, Cathespin B, beta glucuronidase - Activates TNF - alpha, degrades connective tissue and bactericidal
