Granulocytes — the most common type of white blood cell — have small granules that release enzymes when your immune system is under attack. This can happen during an infection, allergic reaction or asthma episode. Granulocytes form in your bone marrow and only live for a few days.

Overview

Types of granulocytes include neutrophils, eosinophils and basophils.

What are granulocytes?

Granulocytes are the most common type of white blood cell. They contain enzyme granules, which form in the cytoplasm (a thick, semi-fluid solution that fills each cell). When inflammation enters your body, granulocytes rush to the area and release their granules to fight infection.

A blood test is the only way to check your granulocyte levels. A high granulocyte count could mean you have some type of infection. A low granulocyte count might point to bone marrow disorders like leukemia or aplastic anemia.

Other names for granulocytes include granular leukocytes, polymorphonuclear leukocytes or PMN cells.

What does it mean if I have immature granulocytes?

Typically, granulocytes fully develop in your bone marrow before traveling into your bloodstream. If there are immature granulocytes in your bloodstream, it could mean there’s a problem with your bone marrow. Or it could simply indicate an early-stage response to infection. Healthcare providers get concerned when immature granulocytes make up 2% of your total white blood cell count.

Pregnant women and newborn babies may naturally have immature granulocytes in their bloodstream. In these cases, immature granulocytes indicate a healthy bone marrow response and it’s not a cause for concern.

Function

What is the function of granulocytes?

Granulocytes work together to rid your body of infection or allergens.

There are four types of granulocytes. Each type has its own combination of chemicals and enzymes in its granules. As a result, each type of granulocyte has a different function:

  • Neutrophils: The most abundant type of granulocyte, these attack bacteria. Each cell can consume up to 20 bacteria in its lifetime. Neutrophils make up about 40% to 60% of all granulocytes in your body. That’s about two-thirds of all your white blood cells.
  • Eosinophils: These granulocytes show up in almost all immune responses, most notably allergies. They also fight off parasites.
  • Basophils: These granulocytes mainly combat allergic reactions. They release histamine (which escorts allergens out of your body) and the blood thinner heparin (which prevents clotting).
  • Mast cells: Mast cells are a type of granulocyte that stays in your tissues rather than circulating in your blood. Like basophils, they contain histamine and heparin. Basophils and mast cells are structurally similar. The main difference is that basophils have a shorter lifespan, and they rush to sites of inflammation at the first sign of trouble.

Anatomy

Where are granulocytes located?

Granulocytes form in your bone marrow and enter your bloodstream when necessary.

What is the normal range for granulocytes?

The normal range for granulocytes is between 1,500 and 8,500 cells per microliter of blood. On a blood test, this might look something like: 1.5 – 8.5 x 10^9/L. This range varies slightly depending on the lab that does the testing.

About 50% to 70% of all the white blood cells in your body should be neutrophils. Eosinophils should account for 1% to 3%, and basophils should make up approximately 0.4% to 1%.

Conditions and Disorders

What common conditions and disorders affect your granulocytes?

Conditions that affect your granulocytes include:

Common signs or symptoms of granulocyte conditions

Symptoms vary depending on the type of condition you have. But people commonly experience:

Common tests to check the health of granulocytes

Your provider can determine your granulocyte count with a complete blood count (CBC), a routine blood test. To find granulocyte levels on your CBC test results, look for the words:

  • Neutrophil or “neut.”
  • Eosinophil or “eosin.”
  • Basophil or “baso.”

These words are often followed by “abs” which is short for “absolute.” This refers to the absolute number of the cells per unit volume.

What are common treatments for granulocyte conditions?

Treatment depends on your situation but could include:

If you have cancer that’s affecting your granulocytes, treatment options may include:

Treatment for immature granulocytes

If immature granulocytes show up in your bloodwork, your healthcare provider may run more tests to find out why.

If you have an infection, then your provider will prescribe the appropriate medications. If cancer is the culprit, then your provider will talk with you about treatment options, which may include surgery, chemotherapy or radiation therapy.

Care

How can I take care of myself?

If you have a condition affecting your granulocyte count, it’s important to protect yourself from infection. Here are some recommendations:

Additional Common Questions

Granulocytes vs. agranulocytes: What’s the difference?

Both are white blood cells, but agranulocytes don’t have any granules in their cytoplasm. (Monocytes and lymphocytes are two examples of agranulocytes.)

A note from Wockr

Granulocytes play a major role in attacking infection, allergens and other irritants that invade your body. When these white blood cells work as they should, your body can effectively protect itself. But if your body doesn’t make enough granulocytes — or if your granulocyte count is too low or too high — it could mean there’s something more significant going on. If you get sick often or are prone to infections, schedule an appointment with a healthcare provider. They can run tests to find the underlying cause and plan appropriate treatment.