WBCs Flashcards
Neutrophils aka
Polymorphonuclear Neutrophilic Leukocytes
Segmenters
Most abundant WBC
Neutrophils
Nucleus: NEU
2 to 5 lobes
Neutrophils
Main function is
phagocytosis, leading to the destruction of foreign particles.
First cell to migrate toward the site of infection
Neutrophils
Diapedesis vs Chemotaxis
• Diapedesis: Movement through blood vessel walls to tissues.
Chemotaxis: Migration towards specific areas guided by chemotactic factors.
EOSINOPHILS
• Increase in
allergic reactions or parasitic infections.
• Nucleus: EO
Bilobed or ellipsoidal, often eccentrically located.
EO
Staining:
Takes up acid eosin dye; cytoplasm contains large orange to reddish-orange granules.
BASOPHILS
• Represent less than____ of all circulating WBCs.
1%
BASO nucleus
• Contain coarse, ‘deep-bluish-purple granules that often obscure the nucleus.
• Allergic Reactions:
Regulate T helper cell responses and stimulate B cells to produce |gE.
Basophils
BASO
• ______induces smooth muscle contraction;_____ acts as an anticoagulant.
Histamine
heparin
MONOCYTES
Nucleus:
Irregularly folded or horseshoe-shaped.
MONOCYTES
Cytoplasm:
Ground-glass appearance with fine dust-like granules.
• Precursor for macrophages
Monocytes
MACROPHAGES
Arise from_____.
Differentiation and cell division occur in_____.
monocytes
tissues
Functions:
. Innate Immunity: Microbial killing,
anti-tumor activity, intracellular parasite eradication, phagocytosis, secretion of cell mediators.
Macrophages
• Activation: Enhanced killing activity when activated by microorganisms or cytokines.
Macrophages
Adaptive immunity:
Present antigens to T and B cells.
Macrophages
Macrophages in the blood
Monocytes
Macrophages in the lungs
Alveolar macrophages, dust cells
Macrophages in the liver
Kupffer cells
Macrophages in the skin
Langerhans cells
Macrophages in the CNS
Microglial cells, microgilia
Macrophages in the bones
Osteoclasts
Macrophages in the kidney
Mesangial cells
Macrophages in the CT
Histiocytes
Macrophages in the lymph nodes
Dendritic cells
Mast cells play a role in_____, but they can also function as____
allergic reactions
antigen-presenting cells (APCs).
They can both enhance and suppress the adaptive immune response.
Mast cells
DENDRITIC CELLS
• Named for long membranous extensions resembling..
nerve cell dendrites
Dendritic cells
• Functions:
• Antigen Capture:
Capture antigens via phagocytosis or endocytosis
Dendritic cells
Antigen Presentation:
Present antigens to T lymphocytes to initiate adaptive immune response.
Dendritic cells
Effectiveness:
Most effective antigen-presenting cell (APC) and potent phagocytic cell.
• Lack specificity, essential for early
defense
NATURAL KILLER CELLS
Eliminate target cells without
prior exposure
NATURAL KILLER CELLS
• First line of defense against virally infected cells, intracellular
pathogens, and tumor cells
NATURAL KILLER CELLS
NATURAL KILLER CELLS
• Mechanism of Cytotoxicity
• Binding Receptors on NK Cells
Inhibitory Receptors:
Activating Receptors:
Deliver inhibitory signals
Trigger cytotoxic mechanisms
NK cells
Healthy cells:
Diseased/cancerous cells:
Inhibitory signals from class I MHC proteins
Lack MHC proteins (“missing self”), activating signals from stress proteins
NATURAL KILLER CELLS
• Cytotoxic Action
Releases these 2 enzymes
Perforins form channels (pores) in target cell membrane
Granzymes enter through channels, mediate cell lysis
NK cells
Elimination of target cells in…
30-60 minutes
NATURAL KILLER CELLS
• Antibody-Dependent Cell Cytotoxicity
(ADCC)
• NK cells recognize and lyse antibody-
coated cells
• Binding through CD16 receptor for Fc
portion of IgG
Monocytes, macrophages, and neutrophils also exhibit ADCC
(ADCC)
Antibody-Dependent Cell Cytotoxicity
External defense
Skin and mucous membrane
Lactic acid
Cilia
Stomach acid
Urine
Lysozyme
Normal flora
Skin and mucous membrane
Biological barriers
Lactic acid
Keeps down growth of microorganisms
Cilia
Moves pathogen out of respiratory tract
Stomach acid
Low pH keeps pathogens from growing
Urine
Flushes out pathogen from the body
Lysozyme
Attacks the cell wall of the microorganisms
Normal flora
Competes with pathogen
Produce antimicrobial peptides
Internal defense
Cells
Pathogen recognition receptors (e.g. Toll-like receptors)
Acute-phase reactants
External defense cells
Participate in phagocytosis
NK cells destroy target cells using granzymes and perforins
Toll like receptors
Help phagocytic cells recognize pathogens
acute phase reactants
Recruit WBCs for phagocytosis
Coat pathogens to enhance phagocytosis
Mop up debris