White Blood Cells and Platelets

How are WBCs evaluated?

by number (analyzer) and morphological appearance (blood smear)

If a patient has a viral infection what type of WBC will be increased?

Lymphocytes

If a patient has a bacterial/fungal infection what type of WBC will be increased?

Neutrophils

If a patient had an allergic reaction what type of WBC will be increased?

Basophils

If a patient has a parasitic infection what type of WBC will be increased?

Eosinophils

All cells are produced in the bone marrow except for what type of cell?

T cells - produced in the thymus

What is the overall function of WBCs?

Mediating immunity

What is the kinetic of leukocytes?

the movement of cells through the stages of development → circulation → tissues

What is the earliest recognizable cell during cell development?

Myeloblast

How can a Myeloblast be identified?

• round/oval nucleus

• finely dispersed, smooth delicate chromatin

• one or more nucleoli

• basophilic non-granular cytoplasm

• high N:C ratio

What is the second cell in neutrophil development?

Promyelocyte

How can a Promyelocute be identified?

• large reddish/blue granules

• round/oval nucleus

• slightly coarser chromatin pattern

• more or more nuclei visible

  • more abundant blue cytoplasm

What is the 3rd stage in neutrophil development and the last stage capable of division?

Myelocyte

How can a Myelocyte be identified?

• primary granules disappear and secondary granules appear

• nucleus is round/oval

• Chromatin is more condensed/clumped and unevenly stained

• more abundant cytoplasm

• Cytoplasm starts to change from blue to prink due to secondary granules

What is the 4th stage of neutrophil development?

Metamyelocyte

How can a metamyelocyte be identified?

• secondary granulation fills in cytoplasm

• nucleus is indented

• Chromatin pattern more condensed and unevenly stained

• No nucleoli present

• cytoplasm is tan/pinkish and more abundant

What is the 5th stage of neutrophil development?

Band neutrophil

How can a band neutrophil be identified?

• Nucleus is horseshoe appearance, and often folded and twisted

• chromatin pattern VERY condensed

• cytoplasm is tan/pink and more abundant

What is the final stage of neutrophil development?

Segmented neutrophil

How can a segmented neutrophil be identified?

• nucleus is segmented into 2-5 lobes

• cytoplasm is tan/pinkish

• chromatin is very condensed and clumped

• secondary granulation fills the cytoplasm

How long does it take to go from a myeloblast to a mature neutrophil?

7-11 days

Development of Eosinophil

• same development stages as neutrophil

• 3-6 days in marrow and 8 hours in circulation

• they can move into tissues and back into circulation and in marrow

• distinguishable in the myelocyte stage by orange granules

Basophil development

• same stages as neutrophil

• 7 days in the marrow, only a few hours in circulation

• distinguishable in the myelocyte stage by dark purple/black granules

What are basophils that are in the tissues called?

Mast cells

What is the first stage of lymphopoiesis?

Lymphoblasts

How can lymphoblasts be identified?

• small-medium sized cells with round nucleus

• loos chromatin and one or more active nucleoli

• scanty agranular cytoplasm

• found mainly in bone marrow

What is the 2nd stage of lymphopoiesis?

Prolymphocytes

How can prolymphocytes be identified?

• difficult to distinguish from lymphoblasts

• moderately condensed chromatin and a round nucleus

• prominent central nucleolus and change in thickness of nuclear membrane

What is the 3rd stage of lymphopoiesis?

Lymphocytes

How can small lymphocytes be identified?

• most common

• skimpy cytoplasm and few azurophilic (red) granules

How can medium lymphocytes be identified?

more abundant cytoplasm that usually contains azurophilic granules

How can large lymphocytes be identified?

• more abundant cytoplasm

• usually stains darker blue

• variable clumped chromatin

What cells can develop from lymphocytes?

Plasma cells

What are plasma cells?

differentiated B-cells capable of secreting immunoglobin or antibodies

How can plasma cells be identified?

• round to oval cell

• cytoplasm is abundant and basophilic with a pale perinuclear halo

• round, eccentrically placed nucleus with coarse chromatin

What is the first stage of Monopoiesis?

Monoblast

How can a monoblast be identified?

• found primarily in bone marrow

• one or 2 noticeable nucleoli

• cytoplasm is nongranular

What is the 2nd stage of monopoiesis?

• have some granulation

• folded/lobulated nucleus

• irregularly shaped cytoplasm that is blue/grey with fine cytoplasmic granules

• can be motile and participate in phagocytosis

What is the 3rd stage of Monopoiesis?

Monocytes

What is the 4th stage of Monopoiesis?

Macrophage

How can a macrophage be identified?

• large, actively phagocytic cells

• variable shape and frequently seen with pseudopods (arms)

• nucleus is typically round and may contain one or two nucleoli

• free or fixed

What is the first stage in Platelet development?

Megakaryopoiesis

Megakaryopoiesis

• product of the myeloid progenitor stem cell

• main purpose to fragment their cytoplasm to make platelets

• megakaryoblast → promegakaryocyte → megakaryocyte → platelet

What is the lifespan of platelets?

7-10 days