White Blood Cells, Spleen and Bone Marrow Flashcards
Neutrophil and other granulocyte maturation steps
Hematopoietic stem cell
Copmmon kmyeloid Progenitor
Myeloblast (Monoblast for monocyte)
N/B/E Promyelocyte (Promonocyte)
N/B/E Myelocyte ( - )
N/B/E Metamyelocyte (MONOCYTE)
N/B/E Bands
Mature cells (monocyte can differentiate into macrophage in blood or myeloid dendritic cell in tissue)
Different Neutrophil Pools and stimulation factors
Proliferative = all precursors up to myelocyte (those that can continue to divide). Stimulated by GM-CSF and IL3, 6
Maturation Pool = Metamyelocytes and Bands undergoing final morphologic changes
Stimulated by IL-3 and CSF
Circulation Pool and Margination pool
Margination is inhibited by adrenaline and corticosteroids resulting in neutrophilia. Increases with severe inflammation causing neutropaenia
Inherited neutrophil defects (6) and their breeds
Pelger Huet - Aust Shep, Autosomal Dom, homozygous lethal
Immature nucleus shape but no function defect
Birman cat Neutrophil Anomaly
- Magenta granules, normal function
Chediak Higashi Syndrome - Persian Cats (auto recessive)
- larged fused vacuoles, may have reduced platelet function
Mucopolysaccharoidoses - heritable LSD
Multiple phenotypic abnormalities, multiple dark magenta granules in neutrophils.
Canine Leukocyte Adhesion Deficiency (CLAD) - Irish Setter
Autosomal recessive
- Neutrophils fail to marginate and thus cannot enter tissues.
Trapped Neutrophil Syndrome - Border Collies
Autosomal recessive
- Cannot exit bone marrow resulting in neutropenia with left shift and monocytosis. Immunodeficient.
Differentials for Neutrophilia and expected leukogram patterns
Stress/glucocorticoid response - results in reduced margination with increased tissue migration of lymphocytes (lymphopaenia). Occasionally release of bands if long term steroid therapy
Adrenaline/excitement - alsoe reduces margination but does not effect lymphocytes (or they may increase)
- Strong inflammatory stimulus causing increased turnowver in BM
Neutrophil production time and lifespan
BM production takes 4-6d, quicker if strong stimulus
Lifespan 6-10 hours, migrate into tissues so hard to know for sure
Causes for neutropenia
Inherited defects
Increased margination - strong inflammatory stimulus, often see degenerative neuts
Immune mediated destruction
Stem cell injury
This may be reversible: viral infection (FPV/CPV) Drugs, Toxins, B12 deficiency
Or irreversible (FeLV, myelofibrosis, myeloproliferative disease, myelodysplastic disease, grey collie cyclical haematopoiesis).
Cytokines that stimulates diffferent granulocyte maturation
Neuts - IL3, IL6
Eosinophils - IL5
Monocytes IL3; M-CSF
What is a myelodysplastic syndrome, clinical presentation.
Variable group of disorder bone marrow stem cell maturation that arise due to mutation sin the stem/progenitor cells.
Most are associated with non-regenerative anaemia but more aggressive/advanced disease can be associated with bi or pancytopaenia
What are the BM findings in MDS
High percentage of dysplastic cells - dysynchrony of nuclear to cytoplasmic maturation
Variable bone marrow cellularity (hypo,. normal, hyper)
Large erythroid precursors
Poor prognostic indicators of BM in MDS
High % of blast cells (>5)
Multiple cytopaenias
Multiple lineages affected
Marked morphologic atypia
Classification of MDS in vet med
MDS - excess blasts = 5-20% myeloblasts, all cell lines have dysplatic changes
Peripheral bi or pan cytopaenias
Variable increase in erythroblasts (in cats can have erythroid hypoplasia)
Associated with FeLV in cats
MDS - refractory cytopaenia = <5% myeloblasts, variable increase in erythroblasts. More indolent disease course and typically only causes peripheral non-regenerative anaemia (normocytic)
MDS RC multilineage - dysplastic in >2 cell lines (in dogs this does not cause peripheral cytopaenis but in cats it does). No increase in myeloblasts (<5%). Typically have a non-regenerative microcytic anaemia.
How are secondary dysmyelopoiesis differentiated from MDS
Lower % of dysplastic cells in BM, and rarely have increase in blasts.
History of something causing dysmyelopoiesis (drugs, toxins, immune mediated disease or neoplasia)
Drugs: phenobarbital, azathioprine, oestrogen, Vinc, cyclophosphamide, hydroxyurea
What is Flow cytometry and how is it used in bone marrow disease
Identifies cell surface proteins on haematopoietic cells and lymphoid cell populations through antigen-antibody binding (using monoclonal Abs for each different marker) and reading of the signal (%) generated by this in a heterogenous population of cells.
This can be used to differentiate clonal expansion of mature lymphoid populations such as in TZL or CLL by determining if the expanded population of lymphocytes is clonal or heterogeneous.
It can also be used to screen BM cells in leukaemia and help to differentiate the cell lineage where morphology and immunocytochemistry cannot (through emerging knowledge of CD protein expression in different cell lines)
What is Myelofibrosis and why does it occur`
replacement of the normal bone marrow with fibrous tissue (usually reticulin > collagen) resulting in effacement of normal haematopoietic cells.
Primary myelofibrosis has not been reported in dogs, but secondary fibrosis can occur as a result of any injury to the marrow stem cells/microvasculature (ie toxins, drugs, immune mediated disease, Pyruvate kinase deficiency causing Fe overload, MDS and Myeloproliferative disease).
The result is interations of HSC with bone marrow stromal cells –> increased JAK2 activation megakaryocyte activation which produce PDGF, FGF and TGF all of which stimulate fibroblast proliferation and production of reticulin which matures to collagen.
What are myeloproliferative diseases and how are they diagnosed .
MPDz can be AML or chronic (rare).
Clonal myeloid stem cell expansion (neoplastic) resulting in >20-30% of BM being composed of blast cells or precursor cells (usually 80-90% of marrow). Often have dysplastic changes present as well. This results in myelophthesis of the remaining cell lines and often atypical blast cells in circulation.
Dx - BM biopsy demonstrating large numbers of blast cells, lineage of which is determined by flow cytometry, immunocytochemistry and morphology (though not always possible to differentiate from Lymphoblastic leukaemia). Expression of myeloid markers CD 11b/c, CD14 and CD80 are common features on flow cytometry among others. Also an absence of B/T cell marker expression (though this is not always the case due to cross lineage expression of these surface antigens)
Erythroid leukaemias do not express any markers that can currently be tested and are instead diagnosed based on morphology, and often have concurrent macrocytic circulating RBC.
