[W2] WBCs - granulocytes Flashcards
(28 cards)
What are the two main myeloid WBC categories?
Granulocytes (neutrophils, eosinophils, basophils) and mononuclear phagocytes (monocytes/macrophages).
What are the functions of neutrophils, eosinophils, and basophils?
Neutrophils: kill bacteria and fungi.
Eosinophils: attack parasites, mediate allergy.
Basophils: release histamine, mediate allergic responses.
What is the common precursor for granulocytes?
CFU-GM (colony-forming unit–granulocyte, monocyte).
What are the stages of granulocyte maturation?
Blast → Promyelocyte → Myelocyte → Metamyelocyte → Band form → Mature cell.
How long do neutrophils circulate?
~7 hours in blood, then ~20 hours in tissue before apoptosis.
What is the lifespan of eosinophils and basophils?
Eosinophils: 8–12h in blood, 8–12d in tissue.
Basophils: 2–3 days in circulation.
Name the 3 types of neutrophil granules and their function.
Primary: Microbicidal (e.g. myeloperoxidase).
Secondary: Enzymatic (e.g. lysozyme, collagenase).
Tertiary: Degradative (e.g. gelatinase, cathepsin).
What are the two key neutrophil actions in infection?
Chemotaxis and phagocytosis.
What is chemotaxis?
Directed neutrophil movement toward infection via gradients (e.g. C5a, LTB4).
What is needed for successful phagocytosis?
Opsonisation with IgG/IgM/complement and receptor binding.
What are the two killing mechanisms inside phagosomes?
O₂-dependent (e.g. hypochlorous acid from MPO).
O₂-independent (e.g. lysozyme).
What are neutrophil extracellular traps (NETs)?
DNA and enzymes extruded to trap/kill microbes outside cells.
What is Chronic Granulomatous Disease?
Inherited NADPH oxidase defect causing defective respiratory burst and granuloma formation.
How does myeloperoxidase deficiency affect immunity?
Often asymptomatic; fungi are the primary risk.
What is the NBT test used for?
Assessing neutrophil oxidative burst (e.g. in CGD).
What methods test neutrophil motility and phagocytosis?
Filter membrane assays, microscopy, and flow cytometry.
Where are eosinophils usually found?
Thymus, GI tract, ovary, uterus, spleen, and lymph nodes.
What are eosinophils’ primary functions?
Combat parasites and mediate allergic inflammation.
What toxic granule contents do eosinophils release?
Eosinophil cationic protein, major basic protein, peroxidase, neurotoxin.
What is Hypereosinophilic Syndrome?
Persistent eosinophilia >6 months, organ infiltration, possibly clonal.
How do basophils differ from mast cells?
Basophils mature in marrow and circulate; mast cells mature in tissue.
What do basophils secrete?
Histamine, heparin, IL-3, IL-4, IL-5, IL-13, TNF-α, GM-CSF.
What is the Basophil Activation Test (BAT)?
Flow cytometry assay for allergy diagnosis (e.g. peanut allergy).
What are the main functions of monocytes/macrophages?
Phagocytosis, antigen presentation, cytokine production.
