LeukocytesLeukocytesFormation, Function and Formation, Function and PathologyPathologyClinical PathologyClinical PathologyKristin M. Canga, RVTKristin M. Canga, RVT

LeukopoiesisLeukopoiesisAll WBC production starts out in red bone

marrow from the same _____________________ ______ _______ that produces RBCs.

The ____________ that act on the PPSC determine which cell type will be produced.

Each WBC has its own stimulus for production.All WBCs differentiate and develop in the bone

marrow except for some _____________________ which start out in bone marrow but develop elsewhere.

At the beginning of leukopoiesis, all WBCs ___________________ (in the bone marrow)

LeukopoiesisLeukopoiesisGranulopoiesis

1. Stem cell 2. Myeloblast

3. Promyelocyte 4. Myelocyte

5. Metamyelocyte 6. Band cell

7. Mature cell (segmented neutrophil, basophil or eosinophil)

Classification of Classification of LeukocytesLeukocytes

Leukocytes may be classified in three different ways:◦____________________________◦____________________________◦__________________________________________

____________________________________

Classification by Defense Classification by Defense FunctionFunction

____________________________◦Phagocytic leukocytes include:

____________________________ ____________________________ ____________________________ ____________________________

_________________ production and cellular ______________◦_________________________

Classification by Shape of Classification by Shape of NucleusNucleus_____________________________

◦Means that the nucleus is _________________, or __________________ Neutrophils Eosinophils Basophils

_____________________________◦Means that the nucleus is varying in

___________ and ______________________ Monocytes

_____________________________◦Means that there is a _____________, rounded

nucleus Lymphocyte

Classification by GranulesClassification by Granules____________________(Presence of granules)

◦________________– granules not attracted to stain◦________________– granules attracted to acidic

stain◦________________– granules attracted to alkaline

stain____________________(Absence of granules)

◦________________◦________________

More on GranulocytesMore on GranulocytesOriginally no granules present

◦PPSC _________________, _________________, __________________, __________________, and finally the various granulocytes based on _________________ granules.

_____________________ produces first set of granules as cells mature◦First set are called

_______________________granulesGolgi Apparatus also produces granules

that are attracted to stain◦__________________ granules are added as cell

matures to determine ____________________ of the cell.

Functions of the Specific Functions of the Specific GranulesGranulesSpecific Granules contain different substances depending on the cell:Neutrophil granules contain ____________________

Aid the cell in killing microorganisms after ___________________

Eosinophil granules contain __________________________________________ De-granulate at site of allergic or anaphylactic reaction to

reduce swellingBasophil granules contain ___________ and

_________ Histamines are released to initiate ___________________ at

site of reaction Inflammation draws ____________________ to site _________________ acts as local anticoagulant to keep blood

flowing to injured/damaged area.

Details of the Details of the GranulocytesGranulocytes

Recall that the granulocytes include:◦_____________________◦_____________________◦_____________________

Granulocytes - NeutrophilsGranulocytes - NeutrophilsAlso called “polymorphonuclear” cellsLobes of the ____________ are

connected by thin ________________ As cell ages, the chromatin of the

nucleus ______________ (squeezes together) and changes shape. (Think “________ and __________”)

As cell becomes ____________, the segments break apart, losing all evidence of chromatin. (Indicates dead cell)

Neutrophil FormationNeutrophil FormationAdult neutrophils take ~___-___ days

to be produced by the bone marrowAre being produced for release as

circulating neutrophils migrate to __________ to fight microorganisms or die of old age.

If high ___________ for neutrophils occurs, they can be produced in less time.

Neutrophil CharacteristicsNeutrophil CharacteristicsGranules are considered to be ________

because they stain neither red, nor blueOften identified on blood smear based

on shape of ______________.PMN adult cells may contain between 2-

4 lobes connected by thin filaments of _____________. ◦Sometimes the chromatin is so thin that

segments look separated.◦(your book says 2-5 lobes, either is fine.)

Neutrophil FunctionNeutrophil FunctionNeutrophils only spend ~____ hours in

circulation before migrating to __________.

Once in the tissue, neutrophils do not ________________ circulation

For this reason, the entire population of circulating neutrophils needs to be replaced ~________ times daily.

If demand is so high that bone marrow cannot supply enough adults, ________ cells will be released

If demand is still too high, progressively _______________ cells will be released.

Neutrophil FunctionNeutrophil FunctionFirst line of defense in the bloodMajor function is __________________ of

invadersCan respond to foreign

microorganisms very quickly.Use the blood as _________________,

squeezing through endothelium cells via ______________. (PLEASE review Figure 9-5 on pg 234 of A&P book)

Neutrophil FunctionNeutrophil FunctionAttracted to site of infection by ______________

◦Chemotaxis is the chemical reaction created between the microorganisms and the tissues that ____________cells.

__________________ cells with granules that contain __________________.◦Lysosomes contain _______________ enzymes

capable of destroying bacteria and viruses upon phagocytosis.

◦Membrane flows around invader and encases it in vacuole that is created, allowing lysosomes to digest invader.

◦____________ is produced through increased _____ absorption, and is toxic to invaders AND ______________.

Neutrophil FunctionNeutrophil FunctionNormally found in tissues that are

constantly susceptible to invasion by microorganisms such as the ________ and _____________tract.

Dead or abnormal neutrophils are disposed of by tissue __________________.

Normal Neutrophil Count in Normal Neutrophil Count in BloodBloodThe neutrophil count in peripheral blood is kept

within a specific range (dogs: 3,000 – 11,400/µL; cats: 2,500 – 12,500/µL)

in healthy animals and is controlled by three factors:

1) Release of mature neutrophils from the ______________ pool in the bone marrow into ________________________blood.

2) Rate of ______________ from peripheral blood into tissue.

3) Entrance of increase numbers of __________ into the neutrophil _________________ line.

Maintaining Normal Neutrophil Maintaining Normal Neutrophil PoolsPools1) Release of mature neutrophils from

the ____________ pool in the bone marrow into the ________________ blood. ________________ supply of mature

neutrophils are “on call” and ready for __________________ release.

Caused by sudden __________________ movement of neutrophils into _____________.

Maintaining Normal Neutrophil Maintaining Normal Neutrophil PoolsPools2) Rate of ___________ from peripheral

blood into ____________.• Total neutrophil population in

peripheral blood can enter the ___________ within a couple of hours

• Triggered by massive acute _____________

Maintaining Normal Neutrophil Maintaining Normal Neutrophil PoolsPools

3) Entrance of increased numbers of _________ into the neutrophil ______________ line. _________ method of control; it takes 3

to 6 days for neutrophils to mature for release

Intravascular Pools of Intravascular Pools of NeutrophilsNeutrophilsThe ______________________________(CNP)

◦Refers to the blood contained in the ____________________________.

◦Blood samples obtained for _______________ analysis contain neutrophils from this pool.

◦The normal range for neutrophils is based on those contained in this pool.

The _____________________________ (MNP)◦Composed of neutrophils that line the

_________ of small blood vessels (not _______________________).

◦These neutrophils are not contained in blood sampled for laboratory analysis.

NeutrophiliaNeutrophiliaDefined: An ______________ in

neutrophils in blood circulationIf overall neutrophils increase, total

________ count increases causing __________________◦To meet increased demand for neutrophils

in tissue, the bone marrow releases its reserve stores of mature, and if necessary, _______________ neutrophils into the blood.

◦If a blood sample is drawn while these neutrophils are in transit, a ___________ than normal number of neutrophils will be included in the sample (__________________)

Neutrophilia in a Periperal Blood Neutrophilia in a Periperal Blood SampleSample

Neutrophilia and StressNeutrophilia and Stress_____________________ leukocytosis:

◦Caused by exercise, ___________, or ________________

◦__________________ release results in a shift of neutrophils from the MNP to the CNP (_______________________)

◦No left shift occurs (no increase in _______ cells)◦Count usually not more than ________ the normal

value◦Should return to normal within ___ minutes of

removal of stimulus◦Most common in _________ and animals

<____mo.

Neutrophilia and StressNeutrophilia and Stress_________________________________________________ -induced

◦Treatment with exogenous steroids◦Steroids inhibit ______________◦Endogenous steroids released in response

to major _____________ illnesses, ________________ disturbances, and __________

◦Neutrophil count nearly _____________ – mature neutrophilia

◦No ____________/ Shift from MNP to CNP

Neutrophis and StressNeutrophis and StressStress Leukogram – ContinuedExpect to see _________________ , and

_______________________.Expect to see _________________ due to lysis

of cells.Expect to see ____________________.Possible see ___________________ in dogsDevelops over several ________ and may

last for several _________.

NeutrophiliaNeutrophiliaOther causes of neutrophilia include:

◦____________________ – mild inflammation yields a leukocyte response similar to __________ severe inflammation yields neutrophilia with a

_______________.

◦Bacterial infections◦Conditions associated with extensive

________damage: Burns, _______________, trauma, extensive ________, neoplasia

◦Extreme leukocytosis (with neutrophilia) may be associated with _____________________ that produce colony-stimulating factors: Hepatozoon canis infections, leukemias, and closed cavity

infections (i.e. _________________, _______________)

LeukemiaLeukemiaLiterally means “_______________ blood”Caused by malignant proliferation of one of

the WBC types◦ In response to some unknown stimulus, stem cells

in bone marrow start producing _______________ cells in one cell line at an __________________ rate.

◦ Abnormal cells show up in blood and bone marrow in large numbers, usually before they are _____________ and cause a dramatic _____________in total WBC count.

◦ Leukemias are considered a form of ____________ and can be ___________ or _____________.

◦ Classified by type of _________ involved◦ Leukemia and leukocytosis may resemble one

another; sometimes the distinction is difficult.

Left shiftsLeft shifts_______________________ Left Shift -

Neutrophilia with some ________ cells present; however, mature, _____________ neutrophils predominate.

________________________ Left Shift – Neutropenia where ____________ neutrophils outnumber _____________neutrophils◦ Usually result of extreme migration of cells into tissues and/or

detrimental effects of toxins.

Degenerative Left Shift

Left ShiftsLeft ShiftsCharacterized by an increase in _________

(immature) neutrophils in the blood. ◦ Note: It is normal for 0-300/µL band cells to be

present in the blood of a healthy canine/feline.Usually associated with _________________

conditionsDemand for neutrophils is ______than bone

marrow pool.Left shifts vary from ___________ (slightly

increased number of bands) to _____________ (metamyelocytes, myelocytes, and rarely- even promyelocytes present in blood)

___________ cytoplasm often present during left shifts

Toxic NeutrophilsToxic Neutrophils

Normal Neutrophils Toxic Neutrophils

Toxic NeutrophilsToxic NeutrophilsDohle Bodies may be noted in

cytoplasm of toxic neutrophils.Dohle Bodies are __________ and

appear similar to _____________ seen in monocytes

Left ShiftLeft Shift

Right shiftRight shift___________________________ – refers to the

presence of ___ or more distinct nuclear lobes within neutrophils.

A right shift reflects prolonged ___________time of neutrophils in blood and can occur as a result of:◦Resolving chronic ___________________◦Glucocorticoid administration◦Hyperadrenocorticism (Cushing’s disease)◦___________________________________ disorders

May develop _____________ when blood film preparation is delayed for more than a few hours.

Hyper-segmented Hyper-segmented NeutrophilNeutrophil

NeutropeniaNeutropeniaNeutropenia will cause the total ________

count to decrease (_____________________)If an infection is out of control, all the

reserves of ____________________ can be used up faster than the bone marrow can replace them.

Such a condition signifies that the body is _____________ against the invading microorganisms.

Prognosis is ________ for a critically ill animal that has __________________ and ___________________________

NeutropeniaNeutropeniaNeutropenia can occur due to:

◦ _______________________ of neutrophils (pseudoneutropenia)

◦ Excessive ___________ demand or destruction of neutrophils Destruction can be _______________-mediated

◦ Reduced or ineffective granulopoiesisConditions that cause neutropenia:

◦ Overwhelming _____________ infections (ex: septicemia)

◦ Idiosyncratic drug reactions may result in neutropenia or pancytopenia (e.g. penicillins, cephalosporins, sulfonamides in dogs and chloramphenicol in cats)

◦ Feline ______________ Virus◦ Canine ____________ Neutropenia (a.k.a. Gray Collie

Syndrome)

Neutropenia in a Peripheral Blood Neutropenia in a Peripheral Blood Smear Smear

EosinophilsEosinophils• Formation: It takes ___ to ___ days to produce

an eosinophil from a PPSC.• Population in circulation ~__-__% of total count• _______________ and ____________ pools are also

found in peripheral blood (like __________________)• Bone marrow contains good supply of mature cells

for release as needed.• Eosinophils migrate into tissue in just a few

_______ where they spend the rest of their lives and undergo the same aging process as neutrophils

• Granules’ color and size vary depending on the ____________.

Eosinophil GranulesEosinophil Granules

Feline

Equine Bovine

Canine

EosinophilsEosinophilsEosinophils are attracted to, and inhibit

local ____________ and hypersensitivity-related reactions.◦Their granules contain anti-________________

substances that are released at the site of the allergic reaction.

They ingest substances associated with the _______________ immune response (antigen-antibody reaction complexes)

They have some ________________ and bactericidal functions◦They are especially effective in phagocytosis of

______ pathogenic organisms, such as ____________, and some parasitic worms but are not protective against most _______________ infections.

EosinophilsEosinophilsNormal Eosinophil Values:

◦dogs: 100-750/µL; cats: 0 – 750/µL) ___________________ is usually a result of:

◦___________________: Skin, respiratory, GI tract◦___________________________: Anaphylaxis, Fleas,

food, grasses, or non-specific allergens. Feline asthma, Chronic ______________ (skin, GI, respiratory, urogenital), Tumor associated (fibrosarcoma, mast cell tumor, lymphoma, etc.)

____________________is difficult to detect and evaluate because their numbers are normally ________.

Feline eosinophilic leukemia. Two neutrophils (arrows) are adjacent to several eosinophils at various stages of development that include segmented, band, metamyelocyte, and myelocyte forms

BasophilsBasophilsFormation:

◦Basophils are produced in the bone marrow from the same PPSCs as other cells

Characteristics: ◦The granules of basophils are ________ soluble

and often washed out during the staining procedure

◦ _____________ are not always visible on a stained smear.

Function: ◦Basophils are the _________ phagocytic of the

granulocytes. ◦ Their granules contain ____________ and

_____________ which are responsible for at least part of their function (not much is known about basophil production or function).

BasophilsBasophils

Above: feline basophil (left); canine basophil (right)

Basophil FunctionBasophil FunctionHistamine and heparin granules

◦_______________ helps initiate __________________ and acute ___________ reactions.

◦_____________________ are attracted to the site of an allergic reaction by ____________________________________ released from the granules.

◦_____________ acts as a localized _____________________ to keep blood flowing to an injured or damaged area.

Basophilia and BasopeniaBasophilia and BasopeniaNormal Basophil Values: ________ in both

dogs and cats ___________________ can be associated

with an __________ or _________________ reaction in the tissue.◦Sometimes ______________ and

_______________________ are seen at the same time.

_______________________: is not clinically significant. Basophils should make up less than ___% of all WBCs in peripheral blood.

AgranulocytesAgranulocytesRecall that agranulocytes include

◦_________________________◦_________________________

Details of AgranulocytesDetails of Agranulocytes• Monocytes are formed in the bone

marrow from the PPSC population.(Maturation: 1. ______________– 2. __________________– 3. ______________)

Lymphocytes originate from the PPSC in the bone marrow; however some travel to ________________ organs to develop and mature before settling into their permanent home in ________________ lymphoid tissue. (More on these later.)

MonocytesMonocytesFormation:

◦Mature much ____________ and stay in the blood _____________ than neutrophils.

◦Total development time is ___-____ hours then they stay in the blood for ___-____hours before entering tissue where they carry out their function.

Description◦Monocytes are slightly __________than a

neutrophil◦Monocytes have a _______-_______cytoplasm,

______________nucleus, and a “_________” chromatin pattern.

MonocytesMonocytesFunction:

◦Major _________________cells; are known as tissue ________________________once in the tissues.

◦Monocytes in the blood are considered _______________ tissue macrophages and are less effective ________________ than they are in the tissue.

MonocytesMonocytesMonocytes enter tissue by the process of

_________________ in response to tissue damage caused by trauma or invading microorganisms.

_________________ respond more quickly to tissue damage, but ________________ stay around longer once they reach the damaged site and have become ________________.

Monocytes can also function in circulating blood to ___________________ damaged blood cells or microorganisms found in the blood (septicemia).

MonocytesMonocytes

M

S

MonocytesMonocytes

M

BC

n

Tissue MacrophagesTissue Macrophages_____________ than monocytes in bloodstreamAre most prevalent in “__________” organs such as

the _________, spleen, lungs, and ____________________________.

Some tissue macrophages are free and wander through tissue, while others become ___________ in specific tissues and remain there for the rest of their life span (e.g. ____________________ cells of liver).

Macrophages are often associated with _________________________ since they have a longer life span than neutrophils.

Collectively, the tissue macrophages and monocytes are known as the ____________________________ phagocyte system.

The Mononuclear Phagocyte The Mononuclear Phagocyte SystemSystemFunctions:

◦Clean up __________ debris that remains after _________________ or infection is ______________

◦____________ processing cells. The MPS can ingest antigens and present them on their cell membranes to the lymphocytes, which will destroy them.

◦Have ability to form multinucleated __________cells in the tissue in response to foreign bodies (ex: granulomas).

◦ Ingest foreign substances. Capable of _________________and _________________. Can

engulf structures beyond the phagocytic capacity of neutrophils such as fungi, protozoa, viruses, and dead neutrophils.

◦Are a major source of colony stimulating factors, _______________ that regulate inflammatory responses.

Fine needle aspirate of a granulomatous skin lesion. Neutrophils are adjacent to large macrophages that have abundant vacuolated cytoplasm and round to oval nuclei. Macrophages are derived from blood monocytes

Buffy coat film from a dog. A large macrophage contains phagocytozed Histoplasma organisms.

Monocytosis & Monocytosis & MonocytopeniaMonocytopenia

Normal Monocyte Values: (dogs: 150-1,350/µL; cats: 0-850/µL)

____________________ is often associated with:◦Chronic inflammatory conditions (particularly

mycotic and other granulomatous infections)◦________________________◦Bacteriemia◦Corticosteroid or ____________ responses

(especially in dogs)_________________________is occasionally seen

but usually has no __________________ significance.

LymphocytesLymphocytes

…To be continued.