Leukocytes - granulocytes Flashcards
Leukocyte are categorized as either
granulocytes or agranulocytes
granulocytes
contain primary and secondary cytoplasmic granules
how can leukocytes leave the blood stream
margination
pavementing (rolling and adhesion)
diapedesis
functions of leukocytes
initiate immune response
defend body against pathogens
chemotaxis (signal WBC to help w/ infection and inflammation)
“true cells” have nucleus and organelles
what signals WBC to respond by chemotaxis
cytokines
Leukopenia
reduced number of circulating WBCs
can be due to bacterial / viral infection exposure to toxins
causes immune response
leukemia
Leukocytosis
elevated WBC count
dehydration, allergy, infection
actively responding to infection producing lots of WBC
hematopoietic stem cells
can self-renew
produce 2 committed precursor cells: myeloid stem cell & lymphoid stem cells
why is self renewal of hematopoietic stem cells important
preserves the pool of stems cells and is critical for feeding the differentiation/maturation pathways
Primary granules
stain blue-purple
azurophilic granules
primary granules contain
lysosomal enzymes
secondary granules contain
lysozyme
alkaline phosphatases
variable staining
types of granulocytes
neutrophils
basophils
eosinophils
Neutrophil
most abundant (60-70% of leukocytes)
6-7 hours -> up to 4 days in CT
multi-lobed nucleus
Neutrophils act to
elimate opsonized bacteria
limit the extent of an inflammatory reaction in CT
enzymes in primary granules
elastase
myeloperozidase
enzymes in secondary granules
lysozymes
other proteases
specific receptors for integrins (ICAM-1 and ICAM-2) enable what
antibacterial and homing function of neutrophil
what WBC is the first to arrive in areas of tissue damage?
neutrophils
neutrophils play an important role in
phagocytosis of bacteria and dead cells
neutrophils are associated with what kind of inflammation
acute inflammation
Neutrophils are the only leukocyte that sometimes have tertiary granules what enzyme do tertiary granules contain
gelatinase (breaks down collagen)
Stab cells (band cells)
immature neutrophils
respiratory burst
bacterial killing by generating hydrogen peroxide and hypochlorous acid
excessive respiratory burst puts cells in oxidative stress
function of neutrophils
Eosinophils
reddish pink-orange granules
2-4% total leukocytes
2 lobe nucleus
circulation 2-6 hours
Tissue lifespan 8-12 hours
Function of Eosinophils
play a role in parasitic infections
reducing the severity of allergic reactions
trigger bronchial asthma
specific hydrolytic enzymes in eosinophils
histaminase
eosinophil peroxidase (EPO)
lysosomal enzymes
major basic protein (neutralizes heparin ; kills parasites)
Eosinophils counteract ______ in hypersensitivity rxns
basophils
True or False
Eosinophils have anti-parasitic function
True
Eosinophils have affinity for what kind of complexes
Ag-Ab (antigen-antibody) complexes
these are destroyed by major basic protein in eosinophils
Basophil
least numerous of the granulocytes
0.5-1% of the total number of leukocytes
blue-violet granules in cytoplasm
can leave circulation
**looks like a mast cell BUT DOES NOT give rise to mast cells
Mast Cells
granules rich in histamine and heparin
derived from the myeloid stem cell - part of immune and neuroimmune systems
mast cells are important in
allergy / anaphylaxis response
involved in wound healing
angiogenesis
immune tolerance
defense against pathogens
Basophils and mast cells develop
from DIFFERENT hematopoietic lineages
Specific basophil granules contain
hydrolytic enzymes
heparin sulfate (anticoagulant)
histamine (vasodilation and increase vascular permeability)
Leukotrienes - slow reacting substance of anaphylaxis ; smooth muscle contraction (asthma)
basophils are used in
type 1 (immediate) hypersensitivity reactions
ex. asthma, hay fever, some allergic dermatitis
anaphylaxis
caused by a severe hypersensitivity reaction
True or False
Eosinophils counteract the effects of basophils
True
