Degranulation Process: Mediator Release & Purpose

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson defines degranulation, goes over the fundamentals of how it occurs, and then covers some of the many effects it has with respect to mast cells.

What is Degranulation?

When small particles of reactive chemicals, called granules, are released from cells like mast cells, this is called degranulation. A mast cell is a type of white blood cell that releases chemicals that play an important role in allergic states, like allergies to dust, atopy, and anaphylaxis.

Mast cells as seen under the microscope.
Mast cells as seen under the microscope.

In this lesson, we are going to go over the general process and purpose of degranulation.

The Process

The way by which degranulation works can be boiled down to two major steps. Again this is just the fundamental process, and lots of nuances beyond this lesson's scope exist.

The first step involves an antigen, an entity or part of an entity that the body perceives as foreign and potentially dangerous. In the case of allergies, this can actually be a relatively harmless thing, like pollen, which the body mistakenly believes is a serious threat when it's actually not.

Be that as it may, when an antigen is recognized by a mast cell, microtubule polymerization occurs within the cell. What in the world is this?

Well, you can think of microtubule polymerization as the building up of a network of roads within the cell. These networks are used to transport various intracellular contents from point A to point B.

So, now that the mast cell has built up a series of roads via microtubule polymerization, this infrastructure is now ready to transport the granules within the cell. But where to?

This is the second step of degranulation. In a calcium-dependent process, the granules are transported from the cell interior to the plasma membrane, which is the cell's outer-most covering, like the peel of an apple. Here, the granules fuse with the plasma membrane and, as a result, reactive chemicals are released outside of the cell.

The second to last step shows the process of degranulation.
The second to last step shows the process of degranulation.

The Purpose

But what for? There are actually many reasons for why mast cells release their reactive chemicals in such a way, chemicals that include the likes of histamine, tumor necrosis factor, tryptases, chymases, and many others. The roles these reactive chemicals serve include the following:

  • They increase the permeability of blood vessels. This can lead to the redness, swelling, and stuffiness of allergies.
  • Bronchoconstriction, or the tightening of the airways. Again, this is something you've probably heard of happening during some allergic responses.
  • The stimulation of nerve cells, which can contribute to the itchiness people feel when they have an allergic reaction.
  • The promotion of, what is essentially, scar tissue formation.

But this lesson shouldn't be so one sided. It seems like all those granules that mast cells have are quite nasty and just harm us. Why do we have these terrible cells in our body!

Well, there is always another side to things.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account