67 Structures, Receptors and Functions of Monocytes and Macrophages Flashcards

1
Q

The major lineage regulator of nearly all macrophages

A

Monocyte/macrophage colony-stimulating factor (M-CSF; also termed CSF-1)

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2
Q

The functions of mononuclear phagocytes

A
  • Phagocytosis, killing, and digestion of microorganisms, particulate material, or tissue debris;
  • Secretion of chemical mediators and regulators of the inflammatory response;
  • Interaction (as dendritic cells) with antigen and lymphocytes in the generation of the immune response;
  • Cytotoxicity, such as killing of some tumor cells; and
  • Other functions specific for macrophages of particular tissues
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3
Q

In the presence of endothelial cells grown on an extracellular matrix, monocytes differentiate along two distinct pathways: toward ______________ or__________________

A

Dendritic cells OR Macrophages

Monocytes that migrate across endothelium in an abluminal to luminal direction differentiate into dendritic cells. In contrast, monocytes that remain in the subendothelial matrix differentiate into macrophages.

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4
Q

Monoblast or Promonocyte

Have characteristic deeply indented, irregularly shaped nuclei with condensed chromatin, and numerous cytoplasmic microfilaments

A

Promonocyte

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5
Q

Promonocyte or Monocyte

Nucleus occupies approximately half the area of the cell and usually is eccentrically placed, chromatin net with fine strands bridging small chromatin clumps, cytoplasm is spread out, stains grayish-blue

Has clear cytoplasmic vacuoles

A

Monocyte

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6
Q

Characteristic of monocyte in phase microscopy

A
  • Nucleus has a distinct chromatin pattern on a cloudy background
  • The cytoplasm is clear gray.
  • Reniform nucleus with a juxtanuclear depression filled by a centrosome and its active undulating movement similar to that of other leukocytes
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7
Q

A striking feature on phase-contrast microscopy that differentiates a small monocyte from a large lymphocyte

A

The ruffled plasma membrane that forms prominent phase-dense folds at the cell surface and edge

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8
Q

Monocyte cytoplasmic granules contain these primary lysosomes:

A

Acid phosphatase and arylsulfatase

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9
Q

TRUE OR FALSE

Most lysozyme produced by mononuclear phagocytes is secreted rather than stored intracellularly.

A

TRUE

Most lysozyme produced by mononuclear phagocytes is secreted rather than stored intracellularly.

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10
Q

TRUE OR FALSE

Monocytes also give a weak but positive periodic acid–Schiff reaction (for polysaccharides) and a Sudan black reaction (for lipids).

A

TRUE

Monocytes also give a weak but positive periodic acid–Schiff reaction (for polysaccharides) and a Sudan black reaction (for lipids).

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11
Q

Frequently used as a marker for monocytes

A

Nonspecific esterase

Monocyte esterases are inhibited by sodium fluoride, whereas the esterases of the granulocytic series are not.

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12
Q

Monocyte esterases are inhibited by _________

A

Sodium fluoride

Monocyte esterases are inhibited by sodium fluoride, whereas the esterases of the granulocytic series are not.

Distinguish marrow monocytes from early myelocytes

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13
Q

Primary lysozyme granules of monocytes

A

Acid phosphatase, arylsulfatase, and peroxidase

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14
Q

Synovium macrophages

A

Type A cells

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15
Q

Human marrow promonocytes and blood monocytes contain granules that comprise two functionally distinct populations

A
  • Those with the enzymes acid phosphatase, arylsulfatase, and peroxidase (analogous to the azurophil granules of the neutrophil)
  • Those that lacks alkaline phosphatase
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16
Q

The fixed macrophages of the spleen

A

Littoral cells

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17
Q

The macrophages of the marrow

A

“nurse cells” of the erythroblastic island

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18
Q

Hepatic macrophages

A

Kupffer cells

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19
Q

Connective tissue macrophages

A

Histiocytes

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20
Q

Spleen macrophages

A

Red pulp macrophages

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21
Q

Bone macrophages

A

Osteoclasts

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22
Q

Surface antigen of macrophages

A

CD68, also known as macrosialin

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23
Q

A relatively constant feature of cells engaged in endocytosis

A

Large number of microvilli at the cell surface

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24
Q

The most constant and characteristic ultrastructural features of macrophages

A

Electron-dense membrane-bound lysosomes

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25
Q

Markers of classical monocytes which comprise 90% to 95% of total circulating monocytes

A

CD14+-bright/CD16-negative cells

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26
Q

When dendritic cells (DCs) mature into ______________________, they have reduced uptake capacity and induce an adaptive immune response or tolerance.

A

Antigen-presenting cells (APCs)

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27
Q

FcRs are divided into three distinct classes:

A

FcRI /CD64
FcRII/ CD32
FcRIII/ CD16

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28
Q

FcR that found on monocytes, macrophages, and activated neutrophils, binds MONOMERIC IgG and can play a role in granulocyte-mediated antibody-dependent cytotoxicity

A

FcRI /CD64

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29
Q

FcR that is present on many cell types, bind COMPLEXED IgG (rather than monomeric), regulates B-cell function and can induce mediator release from myeloid cells and phagocytosis of Ig-coated particles

A

FcRII/ CD32

30
Q

FcR that is expressed by neutrophils, natural killer (NK) cells, and tissue macrophages, bind Ig in IMMUNE COMPLEXES and Ig BOUND TO CELL-SURFACE MEMBRANES

Responsible for antibody-dependent cellular cytotoxicity.

A

FcRIII/ CD16

31
Q

All three FcRs specifically bind the human IgG subclasses _______

A

IgG1 and IgG3

32
Q

Complement receptor that binds dimeric C3bi and is found on both monocytes and macrophages.

A

(CR) 1 (or CD35)

33
Q

Complement receptor that binds the complement fragment C3b.

A

CR3 (or CD11b)

34
Q

Leukocyte integrin (β2) subfamily

A

Lymphocyte function–associated antigen (CD11a)
CR3 (or CD11b)
α-X integrin chain (CD11c)

Share a common β subunit (CD18)

35
Q

Are key molecules responsible for alerting the innate immune system to the presence of microbial infections.

A

Toll-like receptors

36
Q

Toll-like receptors implicated in viral nucleic acid recognition

A

TLRs 3, 7, and 9

37
Q

Elimination of the integrin β2 subunit causes

A

Leukocyte adhesion deficiency type I

38
Q

Non–Toll-Like, Nonopsonic Receptors

A

Scavange receptors (SR-A I/II, MARCO, CD36)

Lectins (Dectin-1, DC-SIGN, Mannose receptor,C-type lectin domains, Cysteine-rich domain, Fibronectin type II domain)

39
Q

Non–Toll-Like, Nonopsonic Receptors: mainly involved in endocytosis, with a predominant intracellular localization.

A

Mannose receptor

40
Q

Non–Toll-Like, Nonopsonic Receptors: a lectin-like receptor that is widely expressed on myeloid cells, with a single immunoreceptor tyrosine-based activation motif (ITAM)–like motif in its cytoplasmic tail

It recognizes β glucans, abundant in fungal walls, including bioactive zymosan particles, and has been implicated in innate resistance to fungal infection.

A

Dectin-1

41
Q

Non–Toll-Like, Nonopsonic Receptors: implicated in mycobacterial recognition as well as in the uptake and exchange of lipids

A

Class B SRs, such as CD36 and SR-BI

42
Q

Non–Toll-Like, Nonopsonic Receptors: plays a role in apoptotic cell uptake and has been implicated in macrophage fusion

A

CD36, thrombospondin

43
Q

Class II MHCs

A

Human leukocyte antigen (HLA)-DR, HLA-DP, and HLA-DQ

44
Q

Induce macrophages to express higher levels of MHC class II antigens

A

IFN-γ

45
Q

Downregulate HLA-DR antigen expression on macrophages

A

Prostaglandin E, α-fetoprotein, and glucocorticoids

46
Q

Type of CD11 expressed on more than 95% of fresh human monocytes and macrophages

A

CD11b

Whereas CD11a is expressed on all leukocytes, CD11b and CD11c are expressed predominantly on monocytes and macrophages, a minor subset of B lymphocytes, and most polymorphonuclear leukocytes.

47
Q

Antibodies specific for CD11b, may block this CR’s ability to bind to CD3bi

It strongly inhibit CR-mediated rosetting of erythrocyte–IgM antibody– complement complexes.

A

OKM1 or Mo1

48
Q

CD11b is expressed on more than _____% of fresh human monocytes and macrophages

A

More than 95%

49
Q

Protein that is expressed on the outer leaflet of apoptotic cells, contributes to apoptotic cell recognition

A

Phosphatidylserine (PS)

50
Q

Pathogenic mechanisms of different organisms on monocyte/macrophage phagocytosis

A
  • Inhibit acidification and fusion (Mycobacterium)
  • Multiply within secondary lysosomes (Leishmania)
  • Escape free into the cytosol (Listeria)
  • Translocate their genomes into the cytoplasm by fusion (enveloped viruses)
51
Q

A major myelomonocytic product of macrophages that is constitutively expressed in vitro but is upregulated in granulomata in vivo

A

Lysozyme

52
Q

Has function in priming of biosynthetic and functional responses associated with cytotoxicity and inflammation in cell-mediated immunity

A

IFN-γ

The initial name of IFN-γ was macrophage activating factor

53
Q

Monocytes differentiate along two distinct pathways:

A

Dendritic cells or macrophages

54
Q

Precursors of monocytes

A

Monoblasts and promonocytes

55
Q

A striking feature on phase-contrast microscopy of monocytes

A

ruffled plasma membrane

56
Q

Elimination of the integrin β2 subunit causes

A

Leukocyte adhesion deficiency type I

57
Q

Receptor thaht is mainly involved in endocytosis, with a predominant intracellular localization

A

Mannose receptor

58
Q

Receptor that displays dual functions, contributing to the clearance of mannose-terminal lysosomal hydrolases and of neutrophil granule glycoproteins such as myeloperoxidase (MPO), as well as of hormones (eg, thyroglobulin) and exocrine secretion products (eg, amylase)

A

Multilectin mannose receptor

59
Q

Splenic macrophages contain a high percentage of HLA-____–positive cells (50%), whereas peritoneal macrophages have relatively few (10–20%)

A

HLA-DR

60
Q

IFN-γ: (induce or downregulate) higher levels of MHC class II antigens

A

induce

61
Q

Prostaglandin E, α-fetoprotein, and glucocorticoids (induce or downregulate) HLA-DR antigen expression

A

Downregulate

62
Q

Circulating half-life of classical or CD14 high monocytes

A

1- to 2-days

63
Q

Subset of monocyte that resemble alveolar but not peripheral macrophages and are dramatically expanded in pathologic conditions, such as sepsis, HIV infection, and cancer

A

CD14+CD16+ monocytes

64
Q

The surface antigen ______ is expressed primarily in T-helper lymphocytes and can act as receptors for HIV type 1 (HIV-1)

A

CD4

65
Q

Chemokine receptor that has been the major coreceptor on monocytes/ macrophages for M-tropic HIV-1 infection

A

CCR5

When in the homozygous state, CCR5Δ32 homozygous individuals are highly protected against acquisition of HIV

66
Q

TRUE OR FALSE

When activated monocytes express a greater potential for cytotoxicity and antimicrobial functions than resident tissue macrophages

A

TRUE

When activated monocytes express a greater potential for cytotoxicity and antimicrobial functions than resident tissue macrophages

67
Q

Central nervous system macrophages

A

Microglia

68
Q

TRUE OR FALSE

Monocytes are not resistant to virus infection, compared with more differentiated macrophages.

A

FALSE

Monocytes are relatively resistant to virus infection, compared with more differentiated macrophages.

These cells selectively adhere to lipid- and platelet-activated endothelium, a precursor to atherogenesis.

69
Q

TRUE OR FALSE

Activated macrophages express a greater potential for cytotoxicity and antimicrobial functions than monocytes

A

FALSE

Activated monocytes express a greater potential for cytotoxicity and antimicrobial functions than resident tissue macrophages

70
Q

Macrophages are rich in lysosomal digestive enzymes, activated by falling pH of approximately _____ within the mature vacuole.

A

6.5