Nepedia
Back to Discover
Advanced Reader
🧬

Basophil

life science Maturity 9-11 Next article →

Basophils are a specialized type of white blood cell. They belong to a group of cells known as granulocytes. Granulocytes are characterized by having small grains, or granules, inside their cytoplasm. Basophils are actually the largest type of granulocyte in the body. However, they are also the least common. They represent only about 0.5% to 1% of the white blood cells circulating in your bloodstream.

Reference ranges for blood tests - white blood cells
Reference ranges for blood tests - white blood cells

These cells serve as important players in the immune system. They are primarily responsible for driving inflammatory reactions. This means they help trigger the body's response to perceived threats. Because of this, basophils are involved in many allergic diseases. These include conditions like asthma, hay fever, and atopic dermatitis. They can even be involved in severe reactions known as anaphylaxis. They also help the body respond to infections caused by ectoparasites, such as ticks.

To understand how they work, we must look at their internal structure. When a basophil is unstained under a microscope, you can see its nucleus. This nucleus usually has two lobes. However, basophils contain large cytoplasmic granules. When these cells are stained for viewing, the granules become so dense that they obscure the nucleus. The name "basophil" comes from the fact that these cells are basophilic. This means they are attracted to and easily stained by basic dyes.

Basophils function through a process called degranulation. This occurs when the cell is activated by a specific stimulus. During degranulation, the cell releases the substances stored within its granules. One key substance is histamine, which acts as a vasodilator. A vasodilator is a chemical that helps increase blood flow to specific tissues. Another important substance is heparin, which is an anticoagulant. An anticoagulant is a compound that prevents blood from clotting too quickly.

Reference ranges for blood tests - white blood cells
Reference ranges for blood tests - white blood cells

In addition to stored chemicals, basophils can generate new substances upon activation. They release proteoglycans like chondroitin and various proteolytic enzymes, such as elastase and lysophospholipase. They also produce lipid mediators called leukotrienes and several different cytokines. One very important cytokine they produce is interleukin-4. This substance is critical for the development of allergies. It also helps the immune system produce IgE antibodies. Some studies in mice suggest basophils may even regulate the behavior of T cells.

How do these cells know when to react? Basophils have specific protein receptors on their cell surfaces. These receptors bind to IgE, which is an antibody used to defend against large parasites. When IgE binds to these receptors, it allows the basophil to respond to environmental substances. These substances might include pollen proteins or antigens from helminths, which are parasitic worms. Interestingly, certain viruses like herpesvirus-6, 7, and 8 can inhibit basophil function. They do this by producing a protein called a CD200 homolog that targets the CD200 receptor on the basophil.

We have a clear history of how these cells were understood. German physician Paul Ehrlich discovered basophils in 1879. Just one year earlier, in 1878, he identified a similar cell in tissues. He called those cells "mastzellen," which we now call mast cells. While mast cells and basophils both store histamine, they are actually different. Mast cells usually stay in the connective tissue and do not circulate in the blood. They also come from different branches of hematopoiesis, the process that creates blood cells. For his groundbreaking discoveries, Ehrlich received the Nobel Prize in 1908.

Today, doctors use basophils to help diagnose medical conditions. They can use a method called the basophil-activation-test, or BAT. In this test, scientists look for the upregulation of certain markers on the cell surface. These markers include CD63 and CD203c. By seeing how these markers react to an allergen, doctors can confirm if a patient has a specific IgE-mediated allergy. This is especially helpful for testing drug reactions or monitoring allergy immunotherapy. While rare, changes in basophil counts can also signal other issues. A low count is called basopenia, while a high count is called basophilia.

657 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (1)
File:Reference ranges for blood tests - white blood cells.png
Reference ranges for blood tests - white...
More to explore

✨ What else?

Related topics you might enjoy

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.