LEUKOPOIESIS NORMAL AND ABNORMAL Barrett W. Dick, M.D. Director, Hematology Laboratories Memorial Medical Center Springfield. IL
Clinical Professor, Pathology and Medicine Southern Illinois School of Medicine June, 2000 Evolution of White Cells
Stem cell vs. Progenitor Cell
Stem cell: a primitive cell that is capable of both self renewal and differentiation. Upon differentiation, it can develop into myeloid or lymphoid lineages. Progenitor cell: a primitive cell beyond
the stem cell stage that is committed to lineage differentiation Evidence for Separate Common Progenitor Cell for B Lymphocytes and Myeloid Progenitor
Philadelphia chromosome is found in CML and a significant fraction of ALL, common
B cell type. Blast crisis in CML is frequently lymphoblastic, almost always B cell type. Granulopoiesis
Myeloblast Promyelocyte Neutrophil Myelocyte
Neutrophil Metamyelocyte Neutrophil band form - "band" Neutrophil segmented form "seg"
To be considered a segmented form, there must be at least one point where the the nucleus is segmented into two lobes with the connection between the containing no visible DNA (1). If there is visible DNA (2), it is not considered a segment. Neutrophil Maturation
When a differential count is performed, traditionally, the device used for tallying the cells is arranged with the least mature cells on the left. This is the historic origin of the term "shift to the left" describing a relative increase in immature forms.
Lymphocyte Transformation Small Lymphocyte Transformed lymphocytes aka:
"Reactive", "Large", "Variant" or "Atypical" Blood Smear Examination Performance of a White Cell Differential
Smear Examination Thin Area Feather Edge
Performance of a White Cell Differential - General Principles Scan at low power: o Identify appropriate thin area
o Evaluate quality of smear High power oil- 50X or 100X: o Scan for abnormal cells and make a qualitative assessment o Perform 200 cell differential o Rescan to confirm that differential is an accurate
representation Confidence Interval for Manual Differentials On a 1-200 cell manual differential, if a cell type is reported as:
o "50%", the 95% C.I. is ~40% - 60% . o 1%, the C.I. is ~0-8% . A statistically meaningful differential - 1000 cell differential required but not practical Conclusions: o Scanning the smear for abnormalities is more
important than the diff o Absolute counts from the machine are more accurate Exceptions to the Absolute Counts "Rule"
% Segs compared % Bands - Ratio of the two defines a "left shift" % Monos - Relative monocytosis is important in some clinical situations o Agranuloctosis/neutropenia- Monocytosis frequently predicts bone marrow recovery
o Relative or absolute monocytosis is a frequent finding in myelodysplastic syndromes Absolute Counts Define Cytoses or Cytopenias
Wbc Normal Ranges (cells/cumm) Neutrophils: 1500-6500 (Caucasians) 800-1200 (African subpopulation
Lymphocytes: 1500-3000 Monocytes: <1000 Eosinophils: <700 Basophils: <200 Seg/Band Ratio: 5-6:1
Relative Monocytes: <10% Principles of Blood Smear Examination
A 200 cell differential is a semi-quantitative estimate of the actual diff because the sampling error is very high - you are looking at a very small sample of a very large population
When a differential is reported, what it should mean is that an experienced individual has examined that smear and, other than what was reported, no significant abnormalities were seen
In practice, because of forced cutbacks in staffing, this currently is unlikely to be the case in most institutions
Conclusion: You better learn to examine blood smears Normal Wbc Found in
Peripheral Blood Segmented Neutrophil Neutrophil Segmented Form
Eosinophil Basophil Basophil
Basophil granules are very soluble. In this example they are partially dissolved and are easily mistaken for toxic granules in a neutrophil. The background cytoplasm in a basophil is gray in contrast to the salmon-pink color in a neutrophil
Small Lymphocyte Large Transformed Lymphocyte In a normal blood smear, 15-17% of the lymphocytes may be large
lymphocytes. Large Granular Lymphocyte Frequently, but arbitrarily included as
reactive lymphocytes. The granules identify them as "killer" cells., Large granular lymphocytes"LGLs" There are at least two distinct subclasses of killer
cells o ADCC: antibody dependent cytotoxic cells; a subclass of CD8 cells. Require the presence of an antibody to be functional o Natural killer cells: do not require the presence of an antibody
Monocyte Monocyte Reactive Lymphocyte
Bluish cytoplasm Granules few and larger Indistinct chromatin, more
intensely stained Vs. Monocyte
Muddy blue-gray cytoplasm Many small azurophilic granules, barely visible "Ropy" chromatin
Variations in Normal Wbc Neutrophil with Toxic Granules Neutrophil band with Toxic
Granules Neutrophil with Dohle Body Dohle Bodies are condensations of
cytoplasmic RNA, stain blue-gray, and have the same significance as toxic granulation. Neutrophil with Dohle Body
Hypersegmented Neutrophil Hypersegmented neutrophils are classically associated with megaloblastic processes. However, they are commonly present when
there is a neutrophilia. Rarely, it is a hereditary abnormality. Hypersegmented Neutrophil in Megaloblastic Anemia
Transformed lymphocytes aka: "Reactive", "Large", "Variant" or "Atypical" Abnormal WBC
Myeloblasts, Auer Rod Lymphoblasts, Acute Lymphocytic Leukemia
Lymphoblasts are usually smaller than myeloblasts and frequently have little or no visible cytoplasm. Myelocyte - Eo/Baso?
Abnormal myelocyte frequently interpreted as having both eosinophil and basophil granules. Most likely this is a normal eosinophil myelocyte with primary granules. In either case the significance is they are virtually only seen in the blood in chronic myeloproliferative disorders.
Pelger-Huet Anomaly The Pelger-Huet anomaly can be either hereditary or acquired. The main features are exaggerated nuclear clumping and hyposegmetation. The latter
manifests itself as "increased " band counts. Pseudo Pelger-Huet Anomaly Cells that look metamyelocytes are almost never found in the hereditary form.
Hypogranular Neutrophils The color of normal neutrophils is due to their granules. When they are poorly granulated they appear gray which is the normal cytoplasmic color.
Sezary's Syndrome Cutaneous T-cell Lymphoma The "cerebriform" nucleus is characteristic of some T cellleukemia/lymphomas
Hairy Cell Leukemia Infectious Organisms Intracellular organisms in HIV
patients, Histoplasma on the left,suspected Cryptosporidium on right.
