Meaning of basophil: Basophils are the least common white blood cell type, releasing histamine and other chemicals that help drive allergic reactions and certain inflammatory responses.

Definition of basophil

A basophil is a type of white blood cell that belongs to a group called granulocytes, cells identifiable under the microscope by granules within their cytoplasm. Basophils are the least common type of white blood cell circulating in the blood.

The granules within a basophil contain chemicals, including histamine, that are released when the cell is activated, contributing to the redness, swelling, and itching associated with allergic reactions. Basophils are also involved in the body's response to certain parasitic infections.

Because basophils release many of the same chemical signals involved in asthma and allergic conditions, their number and activity are sometimes considered alongside other white blood cell types, such as eosinophils, when evaluating a person's allergic or inflammatory response, though basophils normally make up only a small fraction of total white blood cells.

Used in a sentence

The complete blood count showed a basophil count within the normal range.

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Good to know

Basophils make up only a small fraction of circulating white blood cells, so a change in basophil count is often interpreted alongside other white blood cell types rather than in isolation.

Word origin

Where “basophil” comes from

Formed from Greek basis, meaning base, and philos, meaning loving, describing the cell's granules, which readily take up basic dyes used in laboratory staining.

For learning, not diagnosis. This glossary provides general educational information and is not a substitute for advice from a qualified healthcare professional. If you may be experiencing a medical emergency, contact local emergency services.