Basophils and Their Role in Asthma

Basophils are one of the less common types of white blood cells that serve as part of our immune system. They account for only around one percent of white blood cells yet play a central role in the body's frontline defense.

Young jogger using asthma inhaler on the beach.
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Basophils perform a number of important functions. They produced heparin which prevents the blood from clotting too quickly and can "eat" parasites through a process called phagocytosis. But perhaps the most important role they play is in certain inflammatory reactions, particularly those involving allergies.

Basophils and Allergies

Basophils are a part of the innate immune system which triggers a non-specific reaction to anything the body considers harmful. Unlike adaptive immunity, which elicits a targeted response, innate immunity results in a generalized attack. When this happens, the body can experience inflammation, a form of self-protection which often manifests with swelling, pain, fever, and fatigue.

In addition to this, basophils produce a substance called histamine which causes blood vessels to dilate to allow defensive immune cells closer to the site of infection.

But this is not the only time when histamines are produced. When the body is exposed to certain allergens, the immune system can "over-respond" and trigger the release of histamines, causing the inflammation, sneezing, and respiratory problems we associate with allergies.

Association Between Basophils and Asthma Symptoms

The number of basophils in the blood can vary. When the numbers are too low, we say that the person has basopenia. When too high, the person has basophilia. Basophilia is of particular concern to people with asthma as an increase in basophil numbers can translate to an increased production of histamines.

Typically speaking, basophilia is uncommon but one can occur in persons with certain bacterial or viral infections, diabetes, rheumatoid arthritis, eczema, or hypothyroidism. By virtue of the increased cell numbers, basophilia may be associated with the worsening of symptoms in persons with asthma. These can include:

  • Severe inflammation of the lungs
  • Narrowing of the air passages (bronchoconstriction), resulting in wheezing, chest tightness, and shortness of breath
  • Excessive production of mucus, causing coughing and respiratory obstruction

Basophilia is also commonly seen in such illnesses as atopic dermatitis, inflammatory bowel disease (IBD), hemolytic anemia, chronic myelogenous leukemia, and Hodgkin disease.

Role in Managing Asthma

While it remains unclear what role, if any, clinical basophil testing (BAT) may have in the diagnosis or treatment of asthma. However, it does highlight the need for further research to understand the molecular mechanisms of asthma and allergies. By doing so, new treatments and supportive therapies may be developed (including the means to temper the basophil-histamine response).

What we do know is this: with appropriate treatment and the regular monitoring of a person's health, the progressive symptoms of asthma can be minimized or prevented. By contrast, poorly controlled asthma (caused either by inadequate dosing or poor treatment adherence) can lead to permanent and even debilitating lung damage.

In the end, the best way to maximize asthma therapy is to maintain good health, and that includes regular visits to your healthcare provider.

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  • Hoffmann, J.; Knol, E.; Ferrer, L.; et al. Pros and Cons of Clinical Basophil Testing (BAT). Current Allergy and Asthma Reports. 2016;16(8):56.

  • Siracusa, M.; Kim, B.; Spergel, J.; and Artis, D. Basophils and Allergic Inflammation. Journal of Allergy and Clinical Immunology. 2013;132(4):789-801.

By Pat Bass, MD
Dr. Bass is a board-certified internist, pediatrician, and a Fellow of the American Academy of Pediatrics and the American College of Physicians.