Clinical Lab Techniques Lecture 2 - Leukocytes

-cytosis

Suffix that refers to a condition of cells

Leukocytosis

Increase in white blood cells

Leukopenia

Decrease in white blood cells

Neutrophils

Which leukocyte is most common in dogs?

False! Horses have the same number of lymphocytes and neutrophils.

True or false? Horses have more lymphocytes than neutrophils.

True!

True or false? Dogs and cats have much more neutrophils than lymphocytes.

True!

True or false? Ruminants have more lymphocytes than neutrophils.

Bone marrow

Where do all leukocytes develop?

Neutrophil (looks like a sausage link)

Leukocyte that is 2-2.5x the diameter of a red blood cell, with a lobulated nucleus and fine granules in the cytoplasm

• 12-15 micrometers

• 2-2.5x diameter of a RBC

• Lobulated or partially segmented nucleus

• Fine granules in nucleus

• Pale pink or light blue cytoplasm

Describe the morphology of a neutrophil

Heterophils

Another term for neutrophils found in rabbits, guinea pigs, birds, and reptiles

Severe inflammatory disease or toxemia

Toxic neutrophils may be seen secondary to

• Diffuse cytoplasmic basophilia

• Foamy vacuolation of the cytoplasm

• Dohle bodies (RNA)

• Abnormal nuclear shapes

Describe the morphological changes associated with toxic neutrophils

• Primarily defensive

• Accumulate at sites of inflammation

• Phagocytic and microbicidal effects

Identify the functions of neutrophils

• Circulate for 8-10 hours

• Migration into tissue spaces is unidirectional

• Lifespan in tissues is 1-4 days

Describe the life cycle of a neutrophil

-philia or -osis

Suffix referring to a predominance or increased number of a certain cell

-penia

Suffix referring to a deficiency of a certain cell

Neutrophilia

What is the most common cause of leukocytosis?

• Epinephrine release due to fight or flight

• Stress response to corticosteroids

• Acute or chronic inflammation

Identify possible causes of neutrophilia

Neutropenia

What is the most common cause of leukopenia?

• Acute demand or consumption in tissues

• Decreased production in bone marrow

• Ineffective granulopoiesis

• Increased margination

Identify possible causes of neutropenia

Band cells

Immature neutrophils are known as

Left shift

An increase in number of band cells

Degenerative left shift

More immature cells than mature cells

A band cell has a C- or S-shaped nucleus

How can you distinguish a band cell from a mature cell?

Lymphocyte

A leukocyte with a round and eccentric nucleus

• 9-12 micrometers

• Round and eccentric nucleus

• Cytoplasm has scant rim of pale blue

Describe the morphology of a lymphocyte

Lymphocytes

B-cells, T-cells, and memory cells are associated with which type of leukocyte?

B-cells (involves bodily fluids)

Lymphocytes responsible for humoral immunity

T-cells (targets specific cells during infection)

Lymphocytes responsible for cellular immunity

Memory cells

Lymphocytes responsible for reducing lag time, or the time it takes the body to recognize an antigen and produce antibodies

B-cells in the bursa

T-cells in the thymus

Lymphocytes, like all white blood cells, are produced in the bone marrow. Where in the body do T- and B-cells become differentiated?

• Blood → lymph nodes → lymph → blood

• Transit time is 8-12 hours

• May survive for months to years

Describe the life cycle of a lymphocyte

• Excitement

• Antigenic stimulation

• Cancers like lymphosarcoma or lymphocytic leukemia

Identify possible causes of lymphocytosis

• Stress response to corticosteroids

• Disruption of lymphatic circulation

• Lymphosarcoma

Identify possible causes of lymphopenia

Monocyte (looks like a croissant)

Leukocyte with an irregularly shaped nucleus

• 15-20 micrometers

• Irregularly shaped nucleus

• Cytoplasm is abundant blue to blue-gray

Describe the morphology of a monocyte

• Phagocytosis (eats dead tissue)

• Regulation of inflammatory response

• Antigen processing

Identify the function of a monocyte

• Released into blood as immature cells

• Transported into tissues as macrophages

Describe the life cycle of a monocyte

• Inflammation

• Demand for phagocytosis

• Tissue necrosis

• Stress response to corticosteroids

Identify possible causes of monocytosis

Eosinophils (looks like a swaddled baby)

Leukocyte with a lobulated nucleus and prominent granules in the cytoplasm

• 12-20 micrometers

• Lobulated or partially segmented nucleus

• Prominent granules in cytoplasm (round in dogs, rod-shaped in cats, large/round in horses)

Describe the morphology of a eosinophil

• Major role in destruction of parasites

• Limited phagocytic and bactericidal activity

• May play a role in destroying neoplastic cells

Identify the function of a eosinophil

• Circulate in blood for a few hours

• Migration into tissue species is unidirectional

• Lifespan in tissues is several days to weeks

Describe the life cycle of a eosinophil

• The 3 W's

• Worms or parasites

• Wheezes or allergic conditions

• Weird diseases (cancer, rare fungal diseases)

Identify conditions associated with eosinophilia

Stress response to corticosteroids

Eosinopenia can be associated with

Corticosteroids

A stress leukogram refers to the results of

Lymphopenia

What is the most consistent change associated with a stress leukogram?

Basophil

Leukocyte with a lobulated nucleus and cytoplasm with dark purple granules

• 12-20 micrometers

• Lobulated or partially segmented nucleus

• Light purple or gray cytoplasm

• Most species have dark purple granules (lavender in felines)

Describe the morphology of a basophil

Hypersensitivity reactions and inflammation

Identify the function of basophils

• Circulate in blood for a few hours

• Migration into tissues is unidirectional

• Lifespan in tissues is several weeks

Describe the life cycle of a basophil

Allergies or parasites like dirofilaria immitis

Basophilia is associated with

Basophils and monocytes

Low counts of _____ and _____ are not clinically recognized

Progenitor cell

A biological cell that can differentiate into a specific cell type

Basophils

Which leukocyte shares a common progenitor cell with mast cells?

Neutrophils

Leukocyte that is primarily defensive and accumulates at sites of inflammation

Neutrophils

Which leukocyte is associated with band cells?

Monocytes

Which leukocyte is transported into tissues as macrophages?

Eosinophils

Which leukocyte plays a major role in the destruction of parasites?

Mast cells

Leukocyte similar to basophils with a round to oval nucleus that may be obscured by cytoplasmic granules

• Similar to basophils (12-20 micrometers)

• Round to oval nucleus

• Central to eccentric nucleus location

• Numerous small, round, dark purple granules that may obscure the nucleus

Describe the morphology of a mast cell

• Protects the body from external invaders

• Usually exist beneath the skin but travel to bloodstream when they metastasize

Identify the function of a mast cell

Review leukocyte morphology!

Review leukocyte morphology!