What are T Cells: Creation and Function

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  • 0:05 A Journey to the Past
  • 0:32 T Lymphocytes
  • 1:47 CD4+, CD8+, and Memory T Cells
  • 5:06 The Production and…
  • 6:30 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

This lesson will teach about the birth, maturation, and importance of T cells. You'll learn about T lymphocytes, cytotoxic T cells, helper T cells, memory T cells, and more!

A Journey to the Past

We're going to take a short journey to the English countryside, to a time, oh, say about 200 years ago, set in the wonderful Romantic era. Here, we will visit a very wealthy lady who enjoys a cup of tea with milk and biscuits on a daily basis. She's very wealthy and has an entire staff of helpers waiting on her to fulfill her daily tea requirements.

T Lymphocytes

What the wealthy lady doesn't want you to know and what the servant whispers in your ear in disgust is that the milky stuff they are pouring in her tea is actually lymph, which is a clear-to-white fluid in your body. This lymph contains everything from fat to proteins to white blood cells. That's pretty disgusting, but not too unlike real milk.

However, the lady of the manor believes it helps her live longer and gives her skin a healthy glow, so the servants just keep quiet. While I'm not sure about the glow of her skin, the lady may have a point about longevity, since some of the white blood cells carried in the lymph are called lymphocytes.

One type of lymphocyte is fittingly called the T lymphocyte. This is a white blood cell of the adaptive immune system that is involved in the body's fight against infection. The adaptive immune system is the part of your immune system that involves the formation or activation of molecules and cells specific to a certain pathogen. Hence, if the lady of the house drinks this tea, she will be boosting her immune system, which may indeed help her live longer.

CD4+, CD8+ and Memory T Cells

In any case, some of the lady's servants, her tea helpers, are appropriately called the T helper cells. These are a specific subset of T lymphocytes, also known as CD4+ T cells, that help to activate important white blood cells. Once a white blood cell, such as macrophage or dendritic cell, presents a biscuit (the pathogen) to a T helper cell, the T helper cell will immediately spring into action. It will tell other lymphocytes, such as B cells that have encountered the same pathogen, to start producing antibodies.

The antibodies are basically little proteins that are specific to a pathogen. What I mean is there are all sorts of different shapes and sizes of animal biscuits, or crackers. Well, antibodies will be made that are specific to a type of animal cracker once a T helper cell helps to activate an antibody-producing B cell. In addition, T helper cells send out signals using molecules called cytokines to critical cells called cytotoxic T cells. These are a type of lymphocyte, also called a CD8+ T cell, that kills virally infected and cancerous cells.

Once a cytotoxic T cell comes across a cell that it deems unworthy, like one infected by a virus or one that is cancerous, it will release a bunch of chemicals. These chemicals, like the sugar in some hot tea, will dissolve into the surrounding area and enter into the affected cell. Once these chemicals dissolve into the target cell, they will initiate a sequence of events that will lead to the apoptosis, or programmed cell death, of that cell.

Since it's a bit hard to remember that T helper cells are called CD4+ cells and cytotoxic T cells are called CD8+ T cells, I came up with a short diddy to help you:

A lady had helpers and more

Serving her daily from morning till four

But she is so vile

A helper she riled

Poisoned her plate

Just a quarter past eight

With that out of my system, I'd like for you to know that some of the servants have been serving tea for a long time. Therefore, they have a pretty good memory of what tea and milk needs to be poured and which sweets need to be served to the English lady to make her happy.

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