What is a Basophil Cell?

Yazan Hamzeh, Adrianne Baron
  • Author
    Yazan Hamzeh

    I am an inspiring budding scientist, who currently works at a fertility unit. I graduated with BSc (honors) in Genetic Engineering from Jordan University of Science and Technology, and then pursued an MSc in Clinical Embryology at the University of Oxford where I graduated with merit. During the course of academic endeavors, I found a passion in writing, whether it being scientific writing or blog writing. Therefore, I am so glad to be a part of Study.com! I am looking forward to hopefully inspire the many budding students out there.

  • Instructor
    Adrianne Baron

    Adrianne has a master's degree in cancer biology and has taught high school and college biology.

What are basophils? Learn about basophils function, increase basophils, and basophil characteristics. Read about basophil structure and basophil histamine. Updated: 07/01/2021

Table of Contents


What are Basophils?

The human body is almost always exposed to a variety of substances that could compromise its health; to counteract this phenomenon, the human body is equipped with an immune system to protect itself against harmful bodies such as viruses, bacteria, and fungi. A major component in the immune system is white blood cells, which are made of several distinct of groups of cells with specific functions working together to protect the body.

One type of white blood cells is basophils, which are the least abundant type of white blood cells, comprising around 0.5-1% of the white blood cell population. Basophils were first identified in the late 1800s by German scientist Paul Ehrlich, and were initially thought to be unimportant due to their scarcity. Produced in the bone marrow and found all around the body, basophils mediate the immune response by releasing chemicals such as histamine and heparin.

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Basophils: Characteristics

Basophils are mononuclear cells, with diameters ranging from 12-15 μm. They are round in shape, but that usually changes upon migration into tissues. The nucleus of basophils are usually bi-lobed or S-shaped, and are observed to have a purplish-black color upon the use of common basic dyes such as haematoxylin. Basophils have a short life span of about 1-2 days, after which they are degraded.

Basophils: Function

Upon activation by a threat such as foreign invaders or allergic reactions, basophils are said to degranulate, meaning that they release the granules that are stored in their cytoplasm. These granules contain chemicals that are necessary to mediate an immune response, and include heparin, serotonin, histamine, and antibodies. Each of these chemicals portray a role in mediating the immune response; for instance, heparin is a naturally occurring blood thinner that prevents clot formation. Moreover, basophils are the only white blood cells that act on "immune surveillance" by detecting and destroying cancer cells.

Basophils: Histamine

Histamines are nitrogenous compounds with the chemical formula C5H9N3 that are secreted upon the degranulation of basophils. Histamines mediate the immune response by acting as vasodilators, increasing the permeability of blood capillaries to make proteins and other chemicals able to pass through easily, hence increasing the leakiness of the capillaries. This boosts the immune response and initiates what is called an inflammatory response.

Histamines and basophils mainly act upon allergen exposure. Examples of said allergens include but are not limited to: pollen, insect bites, certain foods, and animal fur. Upon the release of histamines and the subsequent vasodilation, the body exhibits physical reactions such as congestion of the nasal cavity, sneezing, red watery eyes, chest tightness, and swollen eyes or lips. These symptoms are commonly known as an allergic reaction, and medications known as antihistamines are taken to reduce these symptoms.

Bashophils: Structure

Basophils, along with other types of white blood cells such as neutrophils and eosinophils, are classified as granulocytes. The term granulocytes originates from the presence of granules in the cytoplasm of these cells. These granules are seen as coarse harsh purplish granules under a microscope when stained.

Basophils: Under Microscope

When a microscopic image of a basophil is desired, a basic dye such as hematoxylin is employed; this dye is positively charged, so it will attach to the negatively charged surface of the nucleus and granules, staining them purple. In the image below, the bilobed structure of the basophil's nucleus is apparent, along with the cell's granular cytoplasm.

A basophil under microscope

basophil under microscope

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Frequently Asked Questions

What is a normal basophil percentage?

The normal basophil percentage is 0.5-1% of the white blood cell population. There should be around 300 basophils per microliter of blood.

What happens if basophils are low?

A low level of basophils is referred to as basopenia. Basopenia could cause an allergic reaction or anaphylactic shock, where symptoms include vomiting, shortness of breath, and lightheadedness.

What causes basophils to be high?

High levels of basophils results in basophilia. Basophilia could result from a variety of factors such as hypothyroidism, myeloproliferative disorders, and autoimmune reactions.

What do basophils do in the immune system?

Basophils contain granules that release chemicals such as histamine and serotonin to mediate the immune response. Basophils also activate mast cells by releasing antibodies called immunoglobulin E (IgE) in order to enhance the immune response.

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