Basophils - Kresser Institute Membership Site

Marker Name: Basophils

REFERENCE RANGES FOR BASOPHILS:

Functional reference range: 0–3%

DESCRIPTION:

Basophils are the least abundant leukocytes (white blood cells) in the circulation. Under normal circumstances, they comprise less than 0.5 percent of circulating blood cells.¹ Mature basophils are found near the marginal zone in the red pulp of the spleen, in the lamina propria of the small intestine, and within lung parenchyma.² Once basophil cells are activated, they promote an increase in eosinophil numbers and participate in the differentiation of macrophages in the lung.² Basophils play an important role in the expulsion of parasites from the intestine and provide detective immunity against parasites that typically gain entry through the skin.^3,4 New research has revealed the important roles that basophils play in protective immunity, immediate-type allergy, and delayed-type allergy.⁵

While found in low numbers in the circulation, basophil numbers can expand rapidly in bone marrow in response to inflammatory signals. Granulocyte-myeloid precursor cells differentiate into basophils when exposed to hematopoietic cytokines, interleukin-3, and thymic stromal lymphopoietin.^4,6 Basophils can be quickly mobilized to the bloodstream, spleen, lung, and liver, including various lymphoid or nonlymphoid tissues.¹ The typical lifespan of a basophil is about 60 hours.² Interestingly, this lifespan does not appear to be lengthened during infection, as it is with some other types of leukocytes.² Thus, increases in basophil levels within the blood are the result of de novo production.⁴

An abnormally high number of basophils is called basophilia or basophilic leukocytosis. Basophilic leukocytosis is an uncommon clinical condition and is most often associated with acute or chronic leukemia.⁷ Causes of basophilia include myeloproliferative disorders, hypersensitivity or inflammatory reactions, and hypothyroidism (myxedema).^7,8

Basopenia is an abnormally low basophil count in the blood. Low basophil counts likely represent increased migration of basophils into tissues or decreased production by the bone marrow. Basopenia is rarely clinically important in isolation, but this laboratory result could prompt further testing. For the purposes of this course, we have left the functional range 0-3% as it is difficult to use basophil values as stand alone indicators of pathologic disease. It is best to view these results as patterns and decide whether further clinical investigation is warranted based off this pattern.

A basophil count is reported within the results of a complete blood count (CBC) with automated differential.⁹ A manual differential or peripheral blood smear may be ordered separately to quantify basophils and to look for morphologic abnormalities.

PATHOLOGICAL/CONVENTIONAL RANGE INDICATIONS:

High in:^5,7,8,10,11

Hypersensitivity reactions
Inflammatory conditions
- Inflammatory bowel disease
- Chronic dermatitis
- Chronic sinusitis
- Asthma
Hypothyroidism (especially myxedema)
Infection (e.g., helminths, varicella, tuberculosis)
Myeloproliferative disorders (e.g., polycythemia vera, myelofibrosis, essential thrombocytosis)
Acute or chronic leukemia
Drugs
- Estrogen administration

Low in:^11-15

Ovulation
Normal pregnancy
Cigarette smoking
Acute allergic reaction
Chronic spontaneous urticaria
Stress reactions (e.g., blood loss, thermal trauma, acute radiation exposure)
Hyperthyroidism
Thymoma
Drugs
- Chronic corticosteroid use

FUNCTIONAL RANGE INDICATIONS:

High in:

Same as conventional indications

Low in:

Same as conventional indications

References: