Exam 2 (L12-20) - No Cases

How do you distinguish between bands and mature neutrophils?

Bands are more uniform in shape. Mature neuts will be segmented

How do horse neutrophils differ from other species?

They're more scalloped/jagged

When do lysosome primary vs. secondary granules appear?

"Primary: late myeloblast/early promyeloctye stage

Secondary: appear in myelocytes"

What do lysosomes contain?

Hydrolytic enzymes and antibacterial agents

What lysosome granules are myeloperoxidase +?

Primary Granules

Which is easier to treat: a myeloid leukemia or a lymphoid leukemia?

Lymphoid leukema

What are heterophils?

Birds, reptiles and other species have a neutrophil equivalent that stains red

What are heterophils often mistaken as?

Eosinophils because they stain red

How can heterophils be distinguished from eosinophils?

Heterophils have more oblong granules while eosinophils have round granules

What cells disappear randomly from blood?

Granulocytes and monocytes

How do lymphocytes, eosinophils and monocytes recycle themselves?

Lymphocytes: tissues to blood

Eosinophils: tissue to lymphatics

Monocytes: tissue to bone marrow

How long are neutrophil's half-life?

Blood: 10-15 hours

Tissues: Few Days

What happens if neutrophils don't encounter bacterial in the blood during their lifespan?

Spontaneous apoptosis

What is the marginating neutrophil pool? What organs have them?

Neutrophils that are loosely attached to endothelium in unopened/inactive capillaries that are not counted on BW (typically found in lungs, spleen, liver etc.)

What causes pseudo-neutrophilia?

Marginalized neuts come out of the inactive capillaries when the animal is stressed, exercising or given epinephrine

What is the half-life of eosinophils?

Blood: Less than a day

Tissue: A week or more

What is the half-life of basophils?

Blood: 1-2 days

Tissue: A few days

What is the half-life of monocytes?

Blood: 1-3 days

Develop into macrophages/DCs in tissues: weeks to months

Where do monocytes have marginating pools?

Lungs

Where do lymphocytes have marginating pools?

Lungs

Where do most lymphocytes reside?

Lymphoid Organs (LN, thymus, GI peyer's patches, other lymphoid tissue)

Only _____% of total lymphocytes in the body are in the blood.

2-5%

Most blood lymphocytes are naive ____ and _____ lymphocytes.

T and B

Between T cells, B Cells and NK cells, which are the most numerous in the body?

T Cells > B Cells > NK Cells

What makes lymphocytes different from other WBCs in terms of their circulation?

Other WBCs "disappear" and don't typically return to where they came from, but lymphocytes typically return to lymphoid organs

What is the spleen's job in blood circulation?

Spleen "cleans" the blood - acts as filter, especially bacteria/organisms

What allows lymphocytes to return back to lymphoid organs?

Bind to HEVs (high endothelial venules) that allow lymphocytes to go from blood to lymphatics

What is special about memory lymphocytes?

Once they recognize an antigen, they will return to the tissue that had that antigen after recirculating

________ lymphocytes don't migrate.

Proliferating

What is the half-life of lymphocytes?

T: years

B: 2-3 weeks individual cells, years for proliferating clones

NK: 2 weeks

Neutrophils are most effective against ______.

bacteria

How do neutrophils detect bacteria?

Chemoattractants

What is required for neutrophils to reach the site of the bacteria?

Adhesions molecules -> Haptotaxis (like chemotaxis except more surface-bound than fluid movement)

What activates neutrophils?

Endothelial cells express L selectin to make neutrophils roll. B2 integrin is expressed and allows neutrophils to hold onto endothelium's IC adhesion molecule (ICAM) so they can migrate through wall to infection site

What are haptotaxis?

Chemoattractants activated by infection. Bind to neutrophils in order to bring them to the source.

What is leukotriene B4?

A chemoattractant that neutrophils release to signal that back-up is needed

Do leukocytes migrate through the endothelium of arteries or veins?

Veins, arteries are too fast

How does myeloperoxidase from neutrophil primary granules kill bacteria?

1. Myeloperoxidase is put into phagocytic granule.

2. NADPH oxidase converts oxygen to superoxide, which mutates to make hydrogen peroxide.

3. Miloperoxidase + hydrogen peroxide + halide (like Cl) -> hypoclorous acid (bleach), which kills phagocytized bacteria"

What are the ways neutrophils kill bacteria?

Hypochlorous Acid (H2O2)

ROS (ie. superoxide free radical)

Collagenase, Acid, Lysozyme

Cationic proteins and peptides (defensins) - not enzymatic

Lactoferrin to bind iron

What are NETs?

Neutrophil Extracellular Traps that are released and bind/kills bacteria, fungi, parasites + some viruses without phagocytosis

Active form of cell death - need superoxide free radicals

Besides neutrophils, what other cells release extracellular traps?

Eosinophils and mast cells

What does NETosis require?

Production of superoxide free radicals

How do eosinophils appear in the cat?

Rod shaped granules

How do eosinophils appear in the horse?

Raspberry Appearance

Most tissue eosinophils are located in _______.

GI mucosa

Eosinophils don't adequately defend against _______ and ______.

bacteria and viruses

What kind of inflammation does eosinophils cause?

Th2 cytokine-induced inflammation

Eosinophils defend against _____.

helminths (roundworms, flukes)

What kind of hypersensitivities do eosinophils produce?

Type 1 hypersensivity allergic reaction

Heartworm disease may show an increase in _________.

Eosinophils

How do eosinophils kill helminths?

Unable to phagocytize because helminths are too big.

Use oxygen metabolites, major basic and cationic proteins, neurotoxins

Where do basophils vs. mast cells mature?

Basophils - Bone Marrow

Mast Cells - Tissue

Which lasts longer: basophils or mast cells?

Mast Cells

Do basophils or mast cells proliferate once mature?

Mast Cells

Do mature basophils go through circulation?

Yes

Do mature mast cells go through circulation?

No

What do basophils respond to?

Allergens, helminths, ectoparasites

What do basophils and mast cells contain in their granules?

Histamine-bound polyanions (ex. heparin) - gives the cell their purple color

Basophils/Mast Cells release _____ and when binding to ________.

Histamine, antigen-IgE

Why is mast cell activation important?

Eosinophil recruitment and expulsion of parasites

______ are rapidly mobilized from marrow in response to inflammatory cytokines and have chemoattractants simliar to neutrophils.

Monocytes

What is the function of monocytes?

Antigen presentation to T lymphocytes and production of cytokines

______ promotes transformation of monocyte to macrophages.

M-CSF

What are M1 vs. M2 macrophages?

"M1 - antimicrobial

M2 - wound repair, tissue remodeling"

______ are more effective than neutrophils in viral, fungal, protozoal and helminth infections.

Macrophage

What free radical is most important in macrophages for killing their targets?

Nitric Oxide

How do macrophages link innate and adaptive immunity?

Have TLR that recognize bacterial molecules

Fc and complement receptors for opsonizing microorganisms

______ are important in wound healing

Macrophages

_______ remove aged or damage cells.

Macrophage

_________ degrade phagocytized RBCs and iron stores and release iron for recycling.

Macrophage

What cells remove blood-borne pathogens?

Red Pulp Macrophages (spleen) and intravascular macrophages (liver, bone marrow, lungs)

What lymphocytes have granules?

Cytotoxic T or NK Cells

What are the function of T lymphocytes?

• Cellular immunity

• CD4 - (Helper T) pathogens and neoplasia

• CD8 (Cytotoxic T) antigen-dependent, viruses and neoplastic, cytokines that effect hematopoiesis"

What can cause false leukocytosis?

• Platelet aggregates

• nRBC presence

• Incomplete lysis of erythrocytes

What can cause false leukocytopenia?

• Clumped/lysed leukocytes

• Clot in sample (trabs WBCs, platelets and some RBCs)

What’s the significance of drumsticks or barr bodies in neutrophils?

Inactivated X chromosomes in females

What’s the significance of neutrophil nuclear blebs?

Unknown significance

What is the May-Hegglin anomaly?

Triad: Neutrophil inclusions + thrombocytopenia + macroplatelets (macroplatelet with big inclusions in a nucleus)

• Typically seen in pugs and humans

• Neuts function normally

• No bleeding tendency, normal platelet function

• MYH9 mutation → heavy chain of non-muscle myosin IIA

What is unique about foal neutrophils?

Have visible primary granules

What species can have Dohle bodies in their neutrophils?

Cats

What species can have toxic granulation of their neutrophils?

Ruminants and horses

How can you tell the difference between a normal neutrophils and a toxic one?

Basophilic, foamy cytoplasm

What is a Pelger-Huet Anomaly?

• Hyposegmentation of granulocytes (just looks like bands and monocytes in the sample) → dark chromatin

• Typically in Australian Shepherds, but also can be in other breeds, horses and cats

• Normal function, no clinical abnormalities

What anomaly may show as a false left shift on bloodwork?

Pelger-Huet → the mature neuts look like bands/monocytes

What is AML?

Acute Myelogenous Leukemia

• Neoplasmia of non-lymphoid cells

• >20% blast in bone marrow

What is CML?

Chronic Myelogenous Leukemia

• Neoplasm of granulocytes

• Leukocytosis w/ marked left shift

• <20% blasts in bone marrow

What causes giant neutrophils?

• Anything that causes RUSHED maturation → Inflammation, IMT (imatinib) and IMHA

• Dysgranulopoiesis → ± neoplasm

• Lymphoma

What is hypersegmentation?

When neutrophils have 5 or more distinct lobes

What causes hypersegmentation?

“Really old neuts”

• Endogenous or exogenous glucocorticoids → stayed in blood longer than normal

• Old blood

• Heat Stroke

• Resolving chronic infections → stayed in blood longer than normal

• Myeloid neoplasms

What deficiencies in dogs and cats cause hypersegmentation?

Dogs → cobalamin deficiency

Cats → folate deficiency

What are botryoid neutrophils?

• Seen in heat stroke

• Form of hypersegmentation where the nucelus looks like spokes of a wheel

What is sideroleukocytes?

WBC that have hemosiderin in their cytoplasms → IMHA

What lymphocyte changes occur in neoplastic conditions?

Neoplastic lymphocytes have granules → lymphoma

What are reactive/transformed/atypical lymphocytes?

Lymphocytes that occur in circulation more than normal

Use “atypical” when unsure if the lymphocyte is reactive or neoplastic

• Dark blue cytoplasm

• Vacuoles

• Indented nuceli

How do monocytes appear on a blood smear?

• Variety of shape nucleus

• Basophilic cytoplasm

• Vacuoles

Cytauxzoon felis

What is the Brazil version of Babesia?

Rangelia

How can you distinguish between basophils and mast cells on a blood smear?

Basophils → segmented nuclei

Mast Cells → round nuclei

Absolute leukocyte counts are important because each leukocyte count has its own _______ and _______.

function and kinetics

What WBC type predominates in the blood of carnivores?

Neutrophils