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Clinical Pathology > Leukocytes > Flashcards

Leukocytes Flashcards

1
Q

What 2 types of information does a leukogram give? What do abnormalities identify?

A
  1. WBC count
  2. WBC morphology

pathological processes without specific diagnosis

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2
Q

Leukocyte morphology:

A

MONOCYTES: large nucleus

NEUTROPHIL: segmented horseshoe nucleus

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3
Q

What is the leukon?

A

all WBC types in an animal including precursors and those in the blood, lymphatics, and tissue

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4
Q

What are the 2 types of mature WBC types? Where are the precursors found?

A
  1. polymorphonuclear - neutrophils, eosinophils, basophils
  2. mononuclear - monocytes, lymphocytes
    (+ mast cells)

bone marrow

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5
Q

What is leukopoiesis? What are the 2 stem cell lines?

A

generation of WBCs from pluripotent hematopoietic stem cells of the bone marrow

  1. myelopoiesis (granulopoiesis) - derived from myeloid stem cells and give rise to eosinophils, basophils, neutrophils, and monocytes
  2. lymphopoiesis - derived from lymphoid stem cells to give rise to B and T lymphocytes
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6
Q

What do neutrophils contain? What are 2 characteristics of their morphology?

A

neutrally staining granules

  1. pale pinky cytoplasm
  2. constricted, multilobulated nucleus
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7
Q

What are heterophils? What do they look like?

A

neutrophil equivalents found in birds, rabbits, and reptiles

contain rod-shaped orange-pink granules

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8
Q

Neutrophils are relatively consistent across species. How are bovine and feline neutrophils unique?

A

BOVINE = brighter pink cytoplasm

FELINE = contain Dohle bodies, angular blue cytoplasmic inclusions

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9
Q

Feline neutrophil:

A

light blue Dohle bodies

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10
Q

What cytokines stimulate stem cells in the bone marrow to become myeloblasts? What are the 5 major steps to neutrophil maturation?

A

TNF-α and TNF-γ

  1. promyelocyte
  2. myelocyte (last mitotic division)
  3. metamyelocyte
  4. band neutrophil
  5. segmented neutrophil
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11
Q

What are the 4 neutrophil pools?

A
  1. proliferative pool (20% of bone marrow) - myeloblast, progranulocyte, myelocyte
  2. maturation and storage pool (80% of bone marrow) - metamyelocyte, band neutrophil, neutrophil)
  3. circulating and marginating pool - measured on CBC and adhered to endothelium
  4. tissues
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12
Q

From what neutrophil pool does a CBC measure?

A

circulating neutrophil pool

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13
Q

What makes a good approximation of the circulating neutrophil pool?

A

circulating neutrophil pool + differential count

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14
Q

What 2 neutrophil pools are not counted in the CBC?

A
  1. marginating neutrophil pool
  2. tissue netrophils
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15
Q

What is the general rule of marginating neutrophil pool count in dogs, horses, calves, and cats?

A

DOGS/HORSES/CALVES - MNP = circulating neutrophil pool

CATS - circulating neutrophil pool = 3x MNP

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16
Q

How can corticosteroids affect neutrophils?

A

causes neutrophils to be released from the marginating pool, which downregulates adhesion molecules responsible for margination and has the potential to double the mature neutrophil count

  • stress leukogram!
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17
Q

What is the predominant leukocyte of health in most species? Ruminants?

A

neutrophils

lymphocytes

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18
Q

What is the half-life of neutrophils? How long do they survive in tissue? How are they destroyed?

A

5-10 hours in circulation, then egresses into tissue

24-48 hours

undergo apoptosis and are broken down by macrophages in the spleen, liver, and bones marrow

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19
Q

When are band neutrophils released into circulation? What is their morphology like?

A

in cases of overwhelming inflammation once the storage pool of segmented neutrophils is depleted

similar cytoplasm to mature neutrophils, but has a U- or S-shaped nucleus with few constrictions

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20
Q

What is the function of neutrophils/heterophils?

A

phagocytosis and defense against microorganisms using bactericidal granules

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21
Q

What is the normal morphology of eosinophils?

A

round cell with red-pink cytoplasm granules and multilobulated nucleus with constrictions

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22
Q

How does the morphology of eosinophils in cats, horses, and sighthounds differ?

A
  • CATS = rod-shaped granules
  • HORSES = large round granules
  • SIGHTHOUNDS = gray granules
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23
Q

What species is this blood smear from? What are the arrows pointing to?

A

bird

  • TOP = heterophil
  • BOTTOM = eosinophil
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24
Q

What cytokines stimulate the maturation of eosinophils from stem cells in the bone marrow? What are the 5 stages of development?

A

IL-5 and IL-3 from mast cells, macrophages, and lymphocytes

  1. promyelocyte
  2. eosinophilic myelocyte
  3. eosinophilic metamyelocyte
  4. eosinophilic band
  5. eosinophil
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25
Q

How long do eosinophils remain in the blood? How long do they stay in tissue?

A

marginated and circulating pools remain in blood from minutes to an hour

last weeks and die in tissue

26
Q

What is the rarest leukocyte in circulation in avian species?

A

eosinophils

27
Q

What tissue do most eosinophils reside in? What is their function? What kind of hypersensitivity are they responsible for?

A

GI mucosa

helminth defense by releasing major basic proteins and generating toxic oxygen radicals

Type I hypersensitivity allergic reactions

28
Q

What is the morphology of basophils?

A

contain granules that are round and dark purple, along with a multilobulated nucleus that is thin and ribbon-shaped

29
Q

How do equine/bovine and cat basophils differ? What is true about dog and cat granules?

A
  • EQUINE/BOVINE = numerous dark purple granules
  • CATS = gray to lavender granules

more sparse granules compared to large animals

30
Q

How many basophils are usually in circulation? What is their half-life like? What promotes their migration to tissue?

A

very low numbers

6 hours

inflammatory cytokines - survives around 2 weeks in tissue

31
Q

What is contained in the granules of basophils? What is their function? What cytokines activate them?

A

most histamine measured in the blood

similar to mast cells - protective immunity against helminths

IL-3, IL-5

32
Q

What are the 2 types of mononuclear cells?

A
  1. lymphocytes
  2. monocytes
33
Q

What is the morphology of lymphocytes like? What can they contain in their cytoplasm? How do equine/bovine ones compare?

A

small round cells with large round nucleus and a high nuclear-to-cytoplasmic ratio

pink granules

larger, with more cytoplasm

34
Q

What 3 cells do lymphoid progenitor cells give rise to? What are the source of most lymphocytes in adult mammals?

A
  1. B lymphocytes
  2. T lymphocytes
  3. natural killer cells

secondary lymphoid tisses: tonsils, LNs, spleen, BALT, GALT

35
Q

What 3 things can happen to lymphocytes in tissues?

A
  1. blastogenesis
  2. return to blood via lymphatics
  3. die
36
Q

How are lymphocytes able to recirculate? What is their half-life like?

A

leave lymph nodes via efferent ducts and enter blood via the thoracic duct

30 mins

37
Q

What are the 2 major pools of lymphocytes

A
  1. circulating pool - only 2-5% of lymphocytes circulate in blood; 50-75% T, 10-40% B, 5-10% NK
  2. marginating pool
38
Q

What is the general lymphocyte function? T-lymphocytes? B-lymphocytes?

A

defense against viruses and tumor cells, immunosuppression

cellular immunity - Th1, Th2

humoral immunity - produces antibodies

39
Q

What are the largest WBCs? What is their morphology like?

A

monocytes - 2 to 4 times larger than mature RBC in diameter

light blue to gray cytoplasm with vacuoles and butterfly/kidney bean-shaped nucleus

40
Q

What cytokines induce the maturation of monocytes? What are the 3 major steps? What are the reserves like in bone marrow?

A

IL-1, IL-3, IL-6

  1. monoblast
  2. promonocyte
  3. monocyte

faster production compares to granulocytes, but have little reserves in the marrow

41
Q

What do monocytes do once they reach tissue? What are 5 examples?

A

differentiate into macrophages

  1. LIVER = Kupffer cells
  2. LUNGS = alveolar macrophages
  3. JOINTS = Type A synoviocytes
  4. CNS = microglial cells
  5. SKIN, LYMPHOID ORGANS = dendritic cells
42
Q

What is the circulating half-life of monocytes? How long do they survive in tissue?

A

0.5-3 days

3 months - Langerhans cells in the skin can survive more than a year

43
Q

What are 4 functions of monocytes/macrophages?

A
  1. phagocytosis of microorganisms, like fungi, helminths, and protozoa, RBCs, and extracellular material
  2. antigen presentation to T-lymphocytes
  3. source of cytokines (IL-1, IL-3, TNF) involved in inflammation and hematopoiesis
  4. tissue repair and remodeling
44
Q

What is the morphology of mast cells like?

A

similar to basophils, with round, purple cytoplasmic granules, but have a circular (not multilobulated) nucleus

45
Q

What cells are not routinely reported on CBC leukogram? What does this presence on a blood film indicate?

A

mast cells

pathology (inflammation or neoplasia) - enteritis, pleuritis, peritonitis, hypersensitivity reactions

46
Q

Where do mast cells reside? Where do they mature> What are 2 functions they have?

A

sub-epithelial locations, like dermis, GIT submucosa, and in any tissues

tissues —> liver, spleen LN

  1. promote inflammatory reactions (hypersensitivity)
  2. fibrosis
47
Q

What is neutrophil toxicity? What does it indicate? 4 examples?

A

morphological changes caused by increased neutrophil production and shortened maturation time in the bone marrow —> inflammation

  1. cytoplasmic basophilia
  2. cytoplasmic vacuolation (foamy)
  3. Dohle bodies
  4. ring form nuclei
48
Q

What is happening in these blood smears?

A

A and C = normal mature and band neutrophil; white cytoplasm with pink granules, long and fairly narrow nuclei and tightly condensed chromatin

B and D = toxic change - less condensed chromatin and bluer cytoplasm due to retention of rRNA

49
Q

What is happening in this blood smear?

A

neutrophil toxicity - Dohle bodies, blue cytoplasmic inclusions of remnant rER associated with left shift

  • commonly seen with toxic granulation
50
Q

What is the Pelger-Huet anomaly? In what 2 animals is this most common?

A

mutation in lamin B receptor gene leading to hyposegmentation of granulocytes - neutrophils look like bands or less mature forms

  1. Australian Shepherds
  2. Arabian horses
51
Q

How does the CBC leukogram of animals with the Pelger-Huet anomaly present?

A

increased band or immature neutrophil count, typically with the animals being entirely healthy (doesn’t affect function of neutrophils)

  • blood film helpful
52
Q

What causes the formation of reactive lymphocytes? What 3 changes are seen?

A

cells proliferate due to antigenic stimulation, usually inflammation

  1. cytoplasm becomes larger and deeply basophilic with perinuclear Golgi clearing and vacuole formation
  2. increased cell size
  3. nucleus becomes variable in shape, less condensed, and may contain nucleoli
53
Q

What is happening in these blood smears?

A

reactive lymphocytes - basophilia, visible nucleoli, increased cytoplasm

54
Q

Ehrlichia in monocyte:

A
55
Q

What bacteria are able to infect white blood cells? Monocytic? Granulocytic?

A

Anaplasmataceae spp.

  • MONOCYTIC: Ehrlichia canis
  • GRANULOCYTIC: Ehrlichia ewingii, Anaplasma phagocytophilum
56
Q

How do monocytic Ehrlichia look within the WBC?

A

form a round morula
- Ehrlichia canis

57
Q

What yeast commonly infects WBCs? What does it look like?

A

Histoplasma capsulatum

purple, spherical, clear halo infecting macrophages and monocytes

58
Q

What are the 2 forms of Cytauxzoon felis that infect blood cells?

A
  1. SCHIZONTS in macrophages burst and release the apicomplexan protozoa
  2. MEROZOITES in RBCs
59
Q

What is the characteristic morphology of Hepatozoon spp. infecting leukocytes?

A

capsular gamont

60
Q

What forms of Toxoplasma spp. infect leukocytes?

A

can infect all warm-blooded animals with cats as DH and IH

tachyzoites infect host cells, causing it to burst and allow free tachyzoites to disseminate and reach other blood cells or tissue

Clinical Pathology (33 decks)

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