Leukocytes: Morphology, Kinetics, & Functions (12) Flashcards
What are these two things?
left: banded neutrophil
right: mature neutrophil
What are primary granules? When do they appear?
main storage site of the most toxic mediators, including elastase, myeloperoxidase, cathepsins, and defensins
late myeloblast/early promyelocyte stage
What are secondary granules? When do they appear?
lactoferrin and matrix metalloprotease 9 (also known as gelatinase B)
myelocytes
What kind of stain is this?
myeloperoxidase stain
What are heterophils?
granulocyte equivalent of neutrophils
can be a challenge to differentiate from eosinophils, especially in histopathology
birds and reptiles
few species of mammals
What are these?
left: heterophil
right: eosinophil
What are the leukocyte kinetics?
What is the half-life of a neutrophil? How long do they survive in the tissues?
5-10 hours
a few days
What are the half-lives of eosinophils and basophils in the blood? How long do they remain in the tissues?
blood:
e: less than one day
b: 2-3 days
in tissues:
e: weeks to months
b: a few days
What are the monocyte kinetics? What do they develop into?
0.5-3 days
marinating pool within lung capillaries
develop into macrophages and dendritic cells in tissues where they survive weeks to months
Where are most lymphocytes?
lymphoid organs (2-5% in blood)
most are naive
What is the homing and recirculation of lymphocytes?
bind to high endothelial venules (HEVs) or activated endothelial cells in other tissues
half-life: 30 minutes
What is the lymphocyte survival for T cells?
years: population vs individual cells
What is the lymphocyte survival for B cells?
2-3 weeks individual cells, proliferating clones for years
What is the lymphocyte survival for NK cells?
half-life 1-2 weeks in the circulation
What are functions of neutrophils?
defense against invading microorganisms, primarily bacteria
recognize chemoattractants, migrate through the tissues and destroy invading bacteria
recognize adhesion molecules
What is haptotaxis?
like chemotaxis except surface-bound movement
crawl using B1-3 integrin molecules binding to appropriate adhesion molecules within the extracellular matrix
What is neutrophil activation?
What are chemoattractants?
IL-8 and other chemokine
C5a, leukotriene B4
bacterial products recognized by TLRs
What do chemoattractants do?
bind to receptors on leukocytes causing their stimulation, polarization, and locomotion
Neutrophils phagocytize things that have been _____
opsonized
Describe the process of the primary granule
myeloperoxidase —> discharged into vacuole assembly of NADPH oxidase
What is the formula for myeloperoxidase?
Cl- + H202 (hydrogen peroxide) —> HOCl (hypochlorous acid) + H2O
What is the mechanism of killing?
myeloperoxidase enhanced H2O2 killing
direct damage from reactive oxygen species (ROS) including the superoxide free radical
What are NETs?
What does NETosis require?
the production of superoxide free radicals with NADPH oxidase enzyme
What are the functions of eosinophils? Where are they generally found?
most tissue eosinophils in GI mucosa
little phagocytic ability
type 2 cytokine-induced inflammation
- type 1 hypersensitivity - allergic reactions
- against helminths
What do you expect the eosinophil and basophil count to be?
both high
How do you kill helminths?
CANNOT phagocytize
oxygen metabolites and major basic protein, eosinophil cationic protein, and eosinophil neurotoxin from granules
Compare and contrast basophils vs mast cells
What is the important function of basophils?
expulsion of parasites and eosinophil recruitment
What are basophil and mast cell functions?
granules: histamine bound polyanions like heparin
basophils recruited to sites of inflammation after exposure to allergens, helminths, ectoparasites
release histamine and other mediators following antigen-IgE binding
contribute to inflammation
What is this?
monocyte
What is this?
monocyte
What are monocyte functions?
migrate into tissue to become macrophages and dendritic cells
rapidly mobilized from marrow in response to inflammatory conditions
What are macrophage functions?
M1: antimicrobial
M2*: wound repair, tissue remodeling
T/F: Macrophages are more effective in viral, fungal, protozoal, helminth infections and less effective in bacterial infections
TRUE
What are some other macrophage functions?
What are t-lymphocyte functions?
recruits and activates various immune cells
What are B lymphocyte functions?
What are NK cell functions?
bind to target tumor cells and virus-infected cells and induce apoptosis similar to cytotoxic T lymphocytes
