MLAB 1315- Hematology Fall 2007 Keri Brophy-Martinez Unit 3: Leukocytes

MLAB 1315- HematologyFall 2007Keri Brophy-Martinez

Unit 3: Leukocytes

NEUTROPHILS

Myelopoiesis - the production and development of myeloid cells in the bone marrow Growth factors (colony-stimulating

factors - CSF’s) and interleukins regulate blood cell development by:

Mediating proliferation Differentiation into cell lines Maturation of hematopoietic progenitor

cells

NEUTROPHILS

Three series of granulocytes (named for colors taken up by granules in Wright’s stain) Neutrophils

Granules stain equally with eosin and methylene blue

Normal in circulation = 42 - 75% Eosinophils

Granules stain mainly red Normal in circulation = 0-4%

Basophils Granules stain mainly with methylene blue Normal in circulation = 0-2%

Maturation of the neutrophilic series

Stem cell - an unspecified cell that gives rise to a specific specialized cell, such as a blood cell Multipotential and cannot be identified

morphologically Can self-renew and differentiate


Myeloblast Size: 10-20µm Cytoplasm

Slight amount/blue

No granules ( possible Auer rods to be discussed in another section)

Nucleus Round/Central

or eccentric Reddish purple 1-3 nucleoli Fine meshlike

chromatin with no clumping

N:C ratio = 4:1


Promyelocyte (progranulocyte)

Size: 10-20µm Cytoplasm

Increased amount/blue Fine, azurophilic,

nonspecific granules present

Nucleus Round/Central or

eccentric Reddish-purple Fine, meshlike

chromatin beginning to clump

1-2 nucleoli N:C ratio = 3:1


Myelocyte (last myeloid cell capable of division)


Increased, bluish-pink (“dawning of neutrophilia”)

Fine azurophilic, specific granules

Nucleus Round or

oval/eccentric Reddish-purple Chromatin loosely

clumped No nucleolus

N:C ratio = 2:1 or 1:1


Metamyelocyte (also called “meta” or “juvenile”)


Moderate amount Specific granules

(neutrophilic, eosinophilic or basophilic)

Nucleus Indented (kidney-bean

shaped) Central or eccentric Purple Clumped chromatin No nucleolus

N:C ratio = 1:1


Band Size: 10-16µm Cytoplasm

Moderate amount Specific granules

(see meta) Nucleus

Elongated, narrow band (sausage) shape with uniform thickness

Central or eccentric Clumped, coarsely

granular chromatin


Segmented neutrophil, eosinophil or basophil Size: 10-16µm Cytoplasm

Neutrophil - specific fine violet pink Eosinophil - red uniform specific granules Basophil - coarse violet blue non-uniform specific granules

(Mast cell is a tissue basophil) Nucleus

Neutrophil - purplish-red, clumped granular chromatin, 2-5 distinct nuclear lobes connected by a filament of chromatin

Eosinophil - deep blue purple, coarsely granular chromatin, 2 distinct lobes

Basophil - deep blue purple, coarsely granular chromatin, 2 nuclear lobes (sometimes obscured by cytoplasmic granules)


Function of the neutrophilic series

Neutrophils - defense against bacterial infections

Eosinophils Regulate inflammation Respond to antigenic stimulation in chronic

allergies Interact with larval stages of some helminthic

parasites Basophils

Histamine in granules plays a role in acute, systemic allergic reactions (sudden release of histamine can cause anaphylactic shock)

Granules also contain heparin

MONOCYTES

Monopoiesis - the production and development of monocytes, macrophages and their precursors. Monocytes are produced in the bone marrow. Their primary function is phagocytosis.

MONOCYTES

Other names for macrophages Histiocytes in the loose connective tissue Kupffer cells in the liver Osteoclasts in the bone Microglial cells in the nervous system Also scattered throughout the body in all organ

tissues (spleen, lung, abdomen, etc.) One monocytes have grown into macrophages, they do not normally reenter the bloodstream except in cases of inflammation

Maturation of the monocytic series

Monoblast Size: 12-20µm Cytoplasm

Blue, moderate amount

No granules Nucleus

Round, oval or slightly folded

Eccentric Reddish-purple Chromatin fine and

thready Vacuoles may be

present 1-2 nucleoli

N:C ratio = 4:1


Promonocyte (difficult to discern) Size: 21-20µm Cytoplasm

Paler gray-blue and abundant “Bleb-like” pseudopods at periphery May contain fine red “dust-like” particles Vacuoles may be present

Nucleus Round with chromatin creases or brain-like folding Central Reddish-purple with light clumping of chromatin 0-2 nucleoli


Promonocyte


Mature monocyte (Normal in circulation: 2-9%) Size: 15-18µm Cytoplasm

Pale gray-blue and abundant Bleb-like pseudopods at periphery, variable shape Numerous fine pale red dustlike granule scattered

throughout Vacuoles common

Nucleus Increased folding or elongated Central Purplish with finer clumped chromatin No nucleoli


Monocyte

LYMPHOCYTES

Normal adult value: 21-51% Produced in the bone marrow

(primary lymphoid tissue)

LYMPHOCYTES

Growth factors cause lymphs to differentiate. They proliferate and mature in the primary lymphoid organs:

LYMPHOCYTES

Thymus - T cells Function

Cellular immune response (they do not produce antibodies) Regulate antibody reactions by helping or suppressing

activation of B lymphs. T cells act as “helper cells” (HIV or AIDS virus causes a destruction of these helper cells), which are instrumental in aiding B cells in antibody production, and “suppressor cells”, which act as a “thermostat” to shut off the system or keep it under control. The helper to suppressor ratio is very important and is normally 2:1.

Protect against viral, bacterial, fungal or protozoan infection Responsible for chronic organ graft rejection. (T cells have

many unique antigens on their cell surfaces, some of which are the HLA - human lymphocyte antigen - markers. Cytotoxic and helper T cells act against these HLA markers if they are foreign to the host organism. HLA markers are instrumental in chronic graft rejection and that is why tissue typing is done to establish a good donor match.)

LYMPHOCYTES

Bone marrow - B cells Function

Humoral (antibody) immune response by transforming into antibody-producing plasma cells

Defense against encapsulated bacteria such as streptococci

Mediate hyperacute organ rejection

LYMPHOCYTES

Null cells - unknown maturation sequence Function

Destroy by lysis target cells (such as tumor cells) by cytotoxins

Play a role in inflammatory response Host defense when stimulated by

interferon against certain viruses (cytomegalovirus - CM, and hepatitis) by killing the virally infected target cell before the virus replicates

LYMPHOCYTES

T and B cell lymphocytes cannot be differentiated morphologically. They are distinguished functionally and by immunologic marker studies (to be discussed later.) Null cells appear as large lymphocytes with azurophilic granulocytes and are called large granular lymphocytes (LGL).

Secondary lymphoid tissue Lymph node, spleen, Peyer’s patches in

intestine and mucosal tissues such as tonsils

Active immune response occurs in above tissues where lymphs communicate and interact with antigen-presenting cells, phagocytes and macrophages

Maturation sequence of lymphocytes

Lymphoblast (which is preceded by a lymphoid stem cell)

Cell size: 10-20µm Cytoplasm

Blue/scanty No granules, Auer

rods are never present

Nucleus Purple, smooth

chromatin Round, central or

eccentric 1-2 nucleoli

N:C ratio = 4:1


Prolymphocyte (difficult to distinguish)


Blue, scanty Usually granules are

absent, but a few azurophilic granules may be present

Nucleus Purple, condensed

chromatin Round or indented,

eccentric 0-1 nucleoli

N:C ratio = 4:1


Mature lymphocyte Cell size: 7-10µm (a typical

normal lymph has a nucleus that is the size of a normal RBC)

Cytoplasm Light blue, scanty to

moderate Few azurophilic granules

may be present Nucleus

Purple, dense, clumped chromatin

Round or indented, eccentric

No nucleoli

Large lymphocytes versus monocytes

Size Large lymph: 12-15µm Mono: 15-18µm

Nucleus Large lymph: clumped, condensed Mono: lacy, brainlike folds

Granules Large lymph: large azurophilic, easy to count Mono: red, fine

Cytoplasm Large lymph: clear, nongranular, may be indented by red

cells Mono: “ground glass” appearance, projection of blunt pseudopod blebs


Variant lymphs Other terms used are reactive, atypical, Downey

cell, transformed, virocyte, plasmacytoid Caused by antigenic stimulants such as viruses,

post-transfusion reactions and organ transplants General characteristics

Increased size due to DNA activity in the nucleus and RNA activity in the cytoplasm

Enlarged and/or monocytoid nucleus Variation in nuclear chromatin pattern Nucleus may contain 1-3 nucleoli Abundant, sometimes foamy or vacuolated cytoplasm Variation in cytoplasmic color - gray-blue to intense blue Absence of granules in cytoplasm

Reactive lymphocyte

Plasma cells

Plasma cells Function is the synthesis and excretion of antibodies

(immunoglobulins) Normally not present in the peripheral blood; comprise

2% of bone marrow cells. (May be seen in the peripheral blood in the disease called multiple myeloma, a disease of uncontrolled production of immunoglobulins.)

End stage of the B lymphocyte Appearance

Size: 10-18µm Cytoplasm is dark blue with perinuclear halo and may contain vacuoles

indicating antibody synthesis Nucleus is round, eccentric, dark purple with dense clumped chromatin

Variant plasma cells Grape or Mott cell - cytoplasm completely filled with red, pink or

colorless globules called Russell bodies Flame cell - cytoplasm stains bright red-staining proteinaceous

material

Plasma cells

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MLAB 1315- Hematology Fall 2007 Keri Brophy-Martinez Unit 3: Leukocytes