LEUKOPOIESISNORMAL AND ABNORMAL

Barrett W. Dick, M.D.Director, Hematology Laboratories

Memorial Medical CenterSpringfield. 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 areao Evaluate quality of smear

• High power oil- 50X or 100X:o Scan for abnormal cells and make a qualitative

assessmento Perform 200 cell differentialo 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 diffo 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

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- "LGL’s"

• 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 Vs. Monocyte

• Bluish cytoplasm • Granules few and

larger • Indistinct

chromatin, more intensely stained

• 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.