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Chapter 26. Blood: III. The White Blood Cells

The peripheral blood contains white blood cells of several types in numbers and proportions that vary between quite narrow limits in health but more widely in disease.

Normal White Blood Count & Differential

As with many biologic parameters, there is no strict definition of normal; however, normal ranges are established by laboratories for their population group. Table 26-1 shows a typical set of normal laboratory values for the United States.

Table 26–1. White Blood Cell Count (WBC), Differential: Normal Values.
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Table 26–1. White Blood Cell Count (WBC), Differential: Normal Values.
Total white blood cell count Adult 4000–11,000/μL
Child (3–11 years) 6000–15,000/μL
Infant 8000–20,000/μL
Differential White Cell Count (Adult) 1 Total Number 2 Percentage 2
Neutrophils 2500–7500/μL 40–75%
Lymphocytes 1500–3500/μL 20–50%
Monocytes 200–800/μL 2–10%
Eosinophils 60–600/μL 1–5%
Basophils 0–100/μL < 1%

1 In infancy and childhood, the proportion of lymphocytes is higher; in the first hours after birth, a lymphocyte count of 8000/μL is considered normal.

2 In general, changes in absolute numbers are of more significance than changes in percentages.

Variations in these parameters, along with changes in leukocyte morphology as seen in blood smears, are important indicators of disease (Table 26-2).

Table 26–2. Broad Categories of Variation in Leukocyte Number and Morphology. 1
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Table 26–2. Broad Categories of Variation in Leukocyte Number and Morphology. 1
Increased Count Decreased Count Important Morphologic Changes
Neutrophils Neutrophil leukocytosis (Table 26–5) Neutropenia (Table 26–7) Changes in maturity, staining, or granules (Table 26–5)
Eosinophils Eosinophilia — —
Basophils Basophilia (rare) — —
Lymphocytes Lymphocytosis (Table 26–3) Lymphopenia (Table 26–3) Changes in maturity or changes of lymphocyte transformation (Table 26–3)
Monocytes Monocytosis (Table 26–4) — Changes in maturity

1 Individual categories are discussed in the text and expanded in further tables as indicated.

Abnormalities in Lymphocyte Count

Lymphocyte and monocyte origin and function have been considered with the immune system (Chapter 4: The Immune Response).

Lymphocytosis—increased lymphocyte count in peripheral blood—is best considered in relationship to other lymphoproliferative diseases (Chapter 28: The Lymphoid System: I. Structure & Function; Infections & Reactive Proliferations). It may occur as (1) an acute immune response, with many activated or transformed lymphocytes circulating in the blood; (2) a chronic immune response, in which most of the circulating lymphocytes resemble resting small lymphocytes; or (3) neoplastic proliferation (Table 26-3).

Table 26–3. Variation in Lymphocyte Parameters in Peripheral Blood.
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Table 26–3. Variation in Lymphocyte Parameters in Peripheral Blood.
Major Conditions Immunology
Lymphocytosis
With features of lymphocyte transformation, ie, medium and large lymphocytes and plasmacytoid cells 1 Active immune ...

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