HSF 2 - Unit 1 Histology: Leukocytes

Question 1

what are leukocytes? how do they leave circulation?

Answer 1

mobile white blood cells; via margination, pavementing (rolling and adhesion) and diapedesis (=extravasation)

Question 2

what do WBCs stick to? how?

Answer 2

endothelial cell surface, squeeze between endothelial cells of capillaries and venules via pseudopodia

Question 3

how do leukocytes get to the site of inflammation?

Answer 3

attracted via chemotaxis to the sites via cytokines

Question 4

what are cytokines?

Answer 4

any cell product that influences another cell, like pheromone

Question 5

how are WBCs categorized?

Answer 5

either granulocytes or agranulocytes

Question 6

what do all WBCs possess?

Answer 6

1’ granules that stain a blue-purple color (azurophilic granules); contain lysosomal enzymes (acid hydrolases)

Question 7

what do granulocytes possess?

Answer 7

specific granules (2’ granules) that are absent in agranulocytes; contain lysozyme and alkaline phosphatases, exhibit variable staining

Question 8

what are the different types of granulocytes? what do they all have in common?

Answer 8

neutrophils, basophils, eosinophils; all have single, multi-lobed nucleus and prominent cytoplasmic granules

Question 9

neutrophils

Answer 9

• most common granulocyte, 40-75% of WBCs, 12-14 micrometers in diameter
• multi-lobed nucleus (3-5) = polymorphonuclear cells (PMNs)
• short-lived; tissue lifespan several hours-days
• few mitochondria, use primarily anaerobic glycolysis
• primary granules of neutrophils also contain unique antimicrobial myeloperoxidase

Question 10

what are the cardinal signs of inflammation?

Answer 10

rubor, calor, tumor, dolore (red, heat, swelling, pain)

Question 11

how do secondary granules stain?

Answer 11

either basophilic or eosinohpilic (“neutral”)

Question 12

what do neutrophils contain?

Answer 12

inflammatory mediators and complement activators; proteases, defensins, lactoferrin, and lysozyme (antibacterial compounds) that are released during inflammatory rxn via degranulation; also have small 3’ granules contain gelatinase (breaks down collagen)

Question 13

what are neutrophils associated with?

Answer 13

acute inflammation, generally lasts several days

Question 14

how do neutrophils move?

Answer 14

using amoeboid

Question 15

neutrophils function in ________, which leads to formation of …

Answer 15

phagocytosis, phagolysosome to digest bacteria

Question 16

how are neutrophils attracted to bacteria?

Answer 16

chemotactic factors

Question 17

how is phagocytosis enhanced?

Answer 17

via opsonization - coating of bacteria with Ab and complement to enhance phagocytosis

Question 18

what is a respiratory burst?

Answer 18

bacterial killing by generating hydrogen peroxide and hypochlorous acid

Question 19

what are stab cells?

Answer 19

band cells, immature neutrophils

Question 20

what is a barr body?

Answer 20

inactive X chromosome in females

Question 21

basophils

Answer 21

• least common of WBCs (<1%), 14-16 micrometers in diamter, bilobed nucleus
• may or may not be circulating equivalent of mast cells in tissue
• lifespan uncertain
• characterized by large, basophilic specific granules

Question 22

what do specific granules contain?

Answer 22

hydrolytic enzymes, heparin sulfate (an anticoagulant), chondroitin sulfate (proteoglycan), histamine (vasoactive amine - vasodilation and increase in vascular permeabililty), leukotrienes (slow reacting substance of anaphylaxis - SRS: smooth muscle contraction; asthma)

Question 23

what is degranulation?

Answer 23

release of granule contents into the extracellular space

Question 24

what counteracts effects of basophils?

Answer 24

eosinophils

Question 25

what is anaphylaxis?

Answer 25

very rapid, severe immune reaction that comes from severe hypersensitivity reaction

Question 26

when is degranulation used?

Answer 26

type I (immediate) hypersensitivity reactions

Question 27

eosinophils

Answer 27

• 1-6% of WBCs, 16 micrometers in diameter, bilobed nucleus
• remain in circulation for about 3-6 hrs before entering tissue, tissue have lifespan of about 8-12 days
• surface receptors for IgE
• large eosinophilic specific granules contain hydrolytic enzymes (histaminase, special peroxidase called eosinophil peroxidase=EPO, lysosomal enz’s, major basic protein)

Question 28

eosinophils are important in _______ rxns…

Answer 28

hypersensitivity, counteract basophilic action becuase they are chemotactically attracted to basophils and mast cells via ECF (eosinophilic chemotactic factor)

Question 29

eosinophils also counteract ______’s effects

Answer 29

ameliorate hypersensitivity rxn’s and histamine; by releasing eosinophil derived inhibitor

Question 30

what does eosinophil derived inhibitor do?

Answer 30

inhibits basophil and mast cell degranulation

Question 31

what is an additional function of eosinophils?

Answer 31

antiparasitic function, especially against flukes (helminths) and affinity for Ag-Ab complexes; parasites and Ag-Ab complexes destroyed by major basic protein and subsequent phagocytosis

Question 32

what are the different types of agranulocytes?

Answer 32

monocytes and lymphocytes; both have single, unlobed nucleus and lack 2’ (specific) granules, but have 1’ (azurophilic) granules

Question 33

monocytes

Answer 33

• 2-10% of WBCs, largest of them all with 16-20 micrometer diameter
• abundant gray-blue/lavender cytosplasm; large indented nucleus
• present in bloodstream 2-3 days, then extravasate, enter tissue, become macrophages (=histiocytes)
• lifespan in tissue is several months

Question 34

what are monocytes?

Answer 34

fixed tissue macrophage; = Kupfer cells in liver, microglial cells in CNS, Langerhans cells in skin, dust cells in lung, osteoclasts in bone

Question 35

monocytes contain abundant…

Answer 35

hydrolytic enzymes

Question 36

when are monocytes active?

Answer 36

subacute to chronic infections, along with lymphocytes

Question 37

monocytes can ______ to become …

Answer 37

fuse together to become epithelioid giant cells in chronic granulomas

Question 38

monocytes also function as …

Answer 38

Ag-presenting cells in lymphoid organs

Question 39

lymphocytes

Answer 39

• 20-45% of WBCs that are active in subactute to chronic infections
• lifespan of days to years
• two size classes (small 6-9 and large 9-16) but these do not correclate with cell types
• characterized by round, densely staining nucleus surrounded by thin rim of cytoplasm
• primary cell of immune system, recirculating, immunocompetent cells
• b cells (10%) and t cells (90%)

Question 40

B-cells

Answer 40

in mammals formed in bone marrow and become immunocompetent there, function in humorally mediated immune response- produce Ab’s; after encountering Ag, undergo multiple divisions to produce clone of Ab-producing plasma cells: amplification or clonal expansion

Question 41

some B-cells and T-cells do not _____, but…

Answer 41

replicate, remain as long-lived memory cells or effector cells

Question 42

what do B-cells function in?

Answer 42

anamnestic response of humoral immunity; premise of vaccination to prevent disease; can also function as Ag-presenting cells

Question 43

what do B-cells have on their cell surface?

Answer 43

HLA (human leukocyte Ag) Type II surface markers and surface immunoglobulins

Question 44

T-cells

Answer 44

• Thymus-dependent lymphocytes
• formed in bone marrow, but migrate to thymus to become immunocompetent
• responsible for cell-mediated immunity; have long lifespan

Question 45

what do T-cells have on their surface?

Answer 45

receptors like those on Ab’s (paratopes) that recognize foreign proteins of Ag’s (epitopes); also have “cluster of differentiation” determinant molecules (CD molecules) on surface that recognize HLA receptors on surface of other cells to prevent self-destruction

Question 46

what are the different types of T-cells?

Answer 46

cytotoxic, suppressor, and helper lymphocytes

Question 47

what are cytotoxic cells?

Answer 47

killer t-cells (Tc/Tk); primary effectors in cell-mediated immunity, tend to be large lymphocytes; recognize cells with foreign surface Ag’s or receptors and kill them; punch holes in plasma membranes

Question 48

what are helper t-cells?

Answer 48

Th; detect invaders, sound chemical alarm, recognize Ag, usually presented by macrophages or B-cell, then secrete lymphokines (cytokines) act as pheromones, stimulate b-cells - antibody production, or Tk cells- kill

Question 49

what are suppressor cells?

Answer 49

Ts; suppress activity of b-cells, dampen immune response, especially to “self” molecules; autoimmune diseases-loss of control of Ts cells

Question 50

what are null cells?

Answer 50

lymphocytes which possess Fc receptors but lack specific cell surface markers of either b- or t-cells; include NK cells; possibly some pleuripotential stem cells; responsible for nonspecific cytotoxicity against virus-infected and tumor cells; also function in antibody-dependent, cell-mediated cytotoxicity (ADCC)

Question 51

what is CBC?

Answer 51

complete blood count: total number of WBCs

Question 52

what is differential cell count?

Answer 52

relative percentages of WBCs

Question 53

high WBCs in circulation indicates what?

Answer 53

infection/tumor; eg: -philia, -osis

Question 54

high neutrophils indicates?

Answer 54

acute, bacteria

Question 55

high lymphocytes indicates?

Answer 55

subacute, viral

Question 56

high eosinophils indicates?

Answer 56

allergies, parasites

Question 57

low WBCs indicates?

Answer 57

immune suppression/tumor; eg: -penia

Question 58

low platelet indicates?

Answer 58

thrombocytopenia