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: Identify appropriate thin area Evaluate quality of smear High power oil- 50X or 100X: Scan for abnormal cells and make a qualitative assessment Perform 200 cell differential 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: "50%", the 95% C.I. is ~40% - 60% . ‘1%’, the C.I. is ~0-8% . A statistically meaningful differential - 1000 cell differential required but not practical Conclusions: Scanning the smear for abnormalities is more important than the diff 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" % Mono’s - Relative monocytosis is important in some clinical situations Agranuloctosis/neutropenia- Monocytosis frequently predicts bone marrow recovery 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- "LGL’s" There are at least two distinct subclasses of killer cells ADCC: antibody dependent cytotoxic cells; a subclass of CD8 cells. Require the presence of an antibody to be functional Natural killer cells: do not require the presence of an antibody

Monocyte

Monocyte

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.