Background

Neutrophils (polymorphonuclear neutrophils [PMNs], segs, polys), the most numerous and important leukocytes in the body's reaction to inflammation, constitute a primary defense against microbial invasion through phagocytosis. These cells can also cause tissue damage by releasing enzymes and endogenous pyrogens.

Immature neutrophils are referred to as "stab" or "band" cells. The term band stems from the appearance of the nucleus, which lacks the lobed shape of the mature cell. Mature neutrophils are called PMNs based on the characteristic segmentation of the nucleus.

This test determines the presence of neutrophilia or neutropenia. Neutrophilia is an increase in the absolute number of neutrophils in response to invading organisms and tumor cells. Neutropenia occurs when too few neutrophils are produced in the marrow, too many are stored in the blood vessel margin, or too many have been used.

Normal reference values in adults

* Absolute neutrophil count (ANC): 3,000 to 7,000/mm³ or 3 to 7 x 10⁹/L

* ANC in Black adults: 1.2 to 6.6 x 10⁹/L

* Differential: 50% of total white blood cell count

* 0% to 3% of total PMNs are stab or band cells

Possible causes of neutrophilia

(>8.0 x 10⁹/L or 8,000/mm³; for Black Americans: >7.0 x 10⁹/L or 7,000/mm³)

* Acute, localized, and general bacterial infections. Also, fungal and spirochetal and some parasitic and rickettsial infections.

* Inflammation and tissue necrosis

* Metabolic intoxications

* Chemicals and drugs causing tissue destruction

* Acute hemorrhage, acute hemolytic transfusion reaction, hemolytic anemia

* Myeloproliferative disease

* Malignant neoplasms

* Some viral and parasitic infections

Ratio of segmented neutrophils to band neutrophils

Normally, 1% to 3% of PMNs are band forms (immature neutrophils).

* Degenerative shift to left: In some overwhelming infections, there is an increase in band forms with no leukocytosis (poor prognosis).

* Regenerative shift to left: There is an increase in band forms with leukocytosis (good prognosis) in bacterial infections.

* Shift to right: Decreased band cells with increased segmented neutrophils can occur in liver disease, megaloblastic anemia, hemolysis, drugs, cancer, and allergies.

* Hypersegmentation of neutrophils with no band cells is found in megaloblastic anemias and chronic morphine addiction.

Possible causes of neutropenia

(<1,800/mm³ or <1.8 x 10⁹/L; Black Americans: <1,000/mm³ or <40% of differential count)

* Causes associated with decreased or ineffective production of neutrophils:

* Inherited stem cell disorders and genetic disorders of cellular development

* Acute overwhelming bacterial infections and septicemia

* Viral infections

* Some rickettsial and parasitical diseases

* Drugs, chemicals, ionizing radiation, venoms

* Hematopoietic diseases

* Causes associated with decreased survival of neutrophils:

* Infections mainly in persons with little or no marrow reserves, older adults

* Collagen vascular diseases with antineutrophil antibodies

* Autoimmune diseases, such as systemic lupus erythematosus

* Drug hypersensitivity

* Splenic sequestration

Clinical alert

Agranulocytosis (marked neutropenia and leukopenia) is often fatal. Patients with agranulocytosis must be protected from infection by means of transmission-based precautions as indicated, with strictest emphasis on hand hygiene practices.

Source: Fischbach FT, Fischbach MA. Fischbach's A Manual of Laboratory and Diagnostic Tests. 10th ed. Philadelphia, PA: Wolters Kluwer; 2018.