Leukocytes Flashcards
What are the stages of leukocyte production?
The most immature stage is the myeloblast (round nucleus, containing one or more nucleoli, and gray–blue cytoplasm)
followed by the promyelocyte (round nucleus with lacey to coarse chromatin and purple granules in gray–blue
cytoplasm),
myelocyte (round nucleus with increased chromatin condensation and lighter blue cytoplasm than the promyelocyte),
metamyelocyte (indented nucleus with increased condensation and light blue cytoplasm), band neutrophil and mature segmented neutrophil.
What is an extreme neutrophilia?
AKA leukaemoid response - this term not ideal
When a marked neutrophilia with left shift back to at least myelocytes occurs in association with an inflammatory condition
What is Pelger Huet anomaly?
Cats (as well as dogs and horses) that are heterozygous for inherited Pelger-Huët anomaly exhibit hyposegmentation of neutrophilic cells. The cells have condensed nuclear chromatin with few or no nuclear constrictions
Nuclei may be round, oval, kidney, band, peanut or bilobed in shape. These heterozygous animals show no clinical signs associated with this disorder. Homozygous affected animals die in utero or shortly after birth.
Pseudo-Pelger-Huët cells may occur transiently with infections (especially FeLV), in myeloid neoplasms or, occasionally, with chemotherapy
What is hypersegmentation (right shift)?
defined as the presence of five or more distinct nuclear lobes within a neutrophil
Hypersegmentation occurs as a normal aging process and most often reflects prolonged transit time in blood, as can occur with resolving chronic inflammation, glucocorticoid administration or hyperadrenocorticism. May also be present in myeloid neoplasms
What is dysgranulopoiesis?
Giant neutrophils with nuclear abnormalities are most often seen in cats with intense inflammatory diseases and/or dysgranulopoiesis
They may exhibit normal nuclear morphology or appear hypersegmented.
Dysgranulopoiesis is seen in acute myeloid leukemias, myelodysplastic syndromes, FeLV infections, and feline immunodeficiency virus (FIV) infections. Neutrophils with donut-shaped nuclei also appear to be more common in cats with intense inflammatory responses, as well as with myeloid neoplasms
What are myeloid neoplasms?
Myeloid neoplasms are characterized by the clonal proliferation of one or more of the nonlymphoid marrow cell lines (granulocytic, monocytic, erythrocytic or megakaryocytic) in bone marrow.
How do mycobacterium appear within neutrophils?
unstained rods within the cytoplasm
How are eosinophils different in cats than other animals
Their granules are rod shaped
When does eosinophilia occur?
disorders that result in increased interleukin (IL)-5 production
Parasites
also occur in association with eosinophilic inflammatory conditions of organs that normally contain numerous mast cells, such as skin, lung and intestine; and may be present in animals with IgE-mediated allergic hypersensitivity reactions, such as flea-bite allergies and feline asthma
Hypereosinophilia syndrome
Chronic eosinophilic leukaemia
When does basophilia occur?
immunoglobulin (Ig)E-mediated disorders. When present, basophilia usually accompanies eosinophilia. Basophilia may occur in some cats with mast cell tumors, primarily non-cutaneous types
When may you see granular lymphocytes?
may be cytotoxic T lymphocytes or NK cells.
Low numbers normal
Increased numbers of granular lymphocytes may occur during acute FIV infections.
Lymphocytes with exceptionally large magenta staining granules may be seen in the blood and bone marrow of cats with metastatic large granular lymphomas
Most of these large granular lymphomas appear to originate as intestinal tumours composed of cytotoxic T lymphocytes. This neoplasm is not associated with FeLV infection.
How do neoplastic lymphocytes appear?
Lymphocytes that are present in high numbers in the blood of cats with chronic lymphocytic leukemia have the morphology of normal lymphocytes. Lymphoblasts and prolymphocytes are present in the blood of some cats with lymphoma and acute lymphoblastic leukemia These neoplastic lymphocytes are large and, compared with normal blood lymphocytes, exhibit increased cytoplasmic basophilia and less condensed nuclear chromatin. Nucleoli may or may not be clearly visible in the nuclei of these neoplastic cells
What do plasma cells look like?
Plasma cells have lower N:C ratios and increased cytoplasmic basophilia compared with resting lymphocytes. The presence of prominent Golgi may create a pale perinuclear area in the cytoplasm. Plasma cells typically have eccentrically located nuclei with coarse chromatin clumping in a mosaic pattern. They are present in lymphoid organs (except the thymus), and are rarely observed in blood even when plasma cell neoplasia (myeloma-related disorders) is present
What is the innate immune response?
Neutrophils, macrophages and natural killer (NK) cells (specialized lymphoid cells) provide the innate immune response, which is the first line of defence against an invading pathogen and does not involve immunological memory.
How can you divide the haematopoietic cells in the bone marrow?
Pluripotent stem cells, capable of self renewal
differentiating progenitor cells;
fully functional mature blood cells.
How can signalment affect WBC counts?
Lymphocytosis in dogs less than 6 months old
Sighthounds have lower WBC counts
Cats have normal lymphocyte counts at birth, then v high, then back to normal by 6m of age
What is the bone marrow pool of neutrophils?
The bone marrow pool consists of the mitotic (dividing)
pool, the maturation pool and the storage pool.
In normal nimals the storage pool of mature neutrophils harbours 5–7 days’ worth of neutrophils. Release from the bone marrow is mediated by various factors, including complement 5a, tumour necrosis factors a and β, G-CSF and GM-CSF.
Only when the demand is great, and the storage pool is depleted, are immature neutrophils released from the maturation pool, and band forms or more immature cells
How are neutrophils involved in disease?
neutrophils can phagocytose organisms and kill or inactivate bacteria, yeasts, fungi or parasites
(using lysosomal enzymes, microbicidal substances and the ‘oxidative burst’). Neutrophils also help to eliminate infected and transformed cells, and modulate the immune and inflammatory responses, and are also involved in coagulation.
What helps to identify a physiological neutrophilia?
No left shift
Concurrent abnormalities
• Lymphocytosis (cats especially)
• Hyperglycaemia
What can help to identify a stress/ corticosteroid neutrophilia?
No left shift Concurrent abnormalities (dogs) • Monocytosis • Lymphopenia • Eosinopenia • Elevated alkaline phosphatase Concurrent abnormalities (cats) • Lymphopenia • Eosinopenia
What are the toxic changes of neutrophils and why?
• Increased cytoplasmic basophilia, as a result of
increased residual cytoplasmic RNA
• Cytoplasmic vacuolation due to loss of granule and
membrane integrity during disturbed maturation.
(Vacuolation can develop as an artefact in stored samples)
• Döhle bodies: these are grey–blue intracytoplasmic
inclusions representing aggregates of cytoplasmic
reticulum. Döhle bodies are found in normal cats and
are not considered to reflect toxic change unless they
are frequent and prominent. (Döhle bodies can develop
as an artefact in stored samples)
• Toxic granulation due to retention of acid
mucopolysaccharides in primary granules (which stain
with Romanowsky stains, unlike the secondary
granules usually present in normal neutrophils)
• Giant neutrophils
• Nuclear swelling
• Doughnut nuclei
Aside from Setters, what other inherited neutrophil disorders are in breeds?
Weimaraners (oxidative metabolic disorder) and Dobermanns (defect in bacterial cell killing).
Chédiak–Higashi syndrome in persians
What is Chédiak–Higashi syndrome?
inherited autosomal
recessive disorder of the microtubules and granules in
leucocytes and other cells, reported in smoke-blue
Persian cats with yellow–green irises. Haematologically, abnormally large eosinophilic granules are seen in neutrophils and eosinophils. Affected cats have bleeding tendencies due to platelet dysfunction. They have low to normal neutrophil counts, and the neutrophils show impaired chemotaxis and bacterial cell killing.
