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About the blood and chronic lymphocytic leukaemia (CLL)

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This page tells you about the blood and chronic lymphocytic leukaemia. You can use these links to go straight to sections about

 

A quick guide to what's on this page

Leukaemia

Leukaemia is cancer of the blood forming system. The blood forming system is found in your bone marrow. The bone marrow is the soft inner part of some of your bones. In most types of leukaemia, abnormal white blood cells are made in the bone marrow. Abnormal white cells do not develop properly so they do not give you the protection from infection that they should.

Because there are too many abnormal white blood cells, they stop the bone marrow producing enough healthy blood cells. The abnormal cells can build up in the lymph nodes and spleen, and cause swelling. They may also cause problems in the liver and central nervous system.

Chronic leukaemia tends to take longer to develop than acute leukaemia. You may have chronic lymphocytic leukaemia for months or years without having many symptoms. It may be stable for months or years before it gets worse.

Chronic lymphocytic leukaemia (CLL)

There are two main types of chronic leukaemia – chronic lymphocytic leukaemia (CLL) and chronic myeloid leukaemia (CML). In CLL, it is a type of white blood cell called lymphocytes that are cancerous. (Lymphocytic in CLL is pronounced lim-fo-sit-ik.)

 

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What leukaemia is

Leukaemia means a cancer of the blood forming system. The blood forming system is found in your bone marrow. The bone marrow is the soft inner part of some of your bones. We have more information about the blood and circulation.

In most types of leukaemia, abnormal white blood cells are made in the bone marrow. These cells can get into the bloodstream and circulate round the body. They do not develop properly and so do not work normally. They don't give you the protection from infection that they should. Because there are too many of these abnormal white blood cells, they stop the bone marrow producing enough healthy blood cells. They can also build up in the lymph nodes and spleen and cause swelling. They may also cause problems in the liver and central nervous system.

There are several types of leukaemia. They are divided into two main groups

Leukaemia is called acute or chronic depending on how fast it develops and gets worse. Acute leukaemia can get worse very quickly. If you are looking for information about acute leukaemia, this is not the right section for you. This section is only about chronic lymphocytic leukaemia in adults.

Chronic leukaemia tends to develop very slowly. You may have it for months or years without having many symptoms. It may be stable for months or years before it gets worse. There are two main types of chronic leukaemia – chronic lymphocytic leukaemia (CLL) and chronic myeloid leukaemia (CML). If you are looking for information about CML, you need to go to the chronic myeloid leukaemia section.

 

Blood cells and leukaemia

To understand how and why leukaemia affects you as it does, it helps to know more about blood cells.

Your body makes blood cells in the bone marrow. The bone marrow is the soft inner part of your bones. You make blood cells in a controlled way, as your body needs them.

All blood cells start as the same type of cell, called a stem cell. This stem cell then develops into

  • Myeloid stem cells – which become white blood cells called monocytes and neutrophils (a type of granulocyte)
  • Lymphoid stem cells – which become white blood cells called lymphocytes
  • Erythroblasts – which become red blood cells
  • Megakaryocytes – which become platelets

The diagram below helps to explain this.

Diagram showing how blood cells are made

The type of chronic leukaemia you have tells you which type of white blood cell has become cancerous. In chronic lymphocytic leukaemia (CLL), it is the lymphocyte white blood cells that are cancerous.

Diagram showing the cells CLL affects

 

What blasts are

New, immature blood cells of any type are called blasts. Some blasts stay in the bone marrow to mature. Some travel through the blood system to other parts of the body before they mature. Even leukaemic white cells mature to some extent. So it is possible to have leukaemic blasts – in other words very young leukaemic white blood cells.

 

How leukaemia affects the blood cells

White blood cells help to fight infection. If you have abnormal white blood cells they cannot fight infection so well. You may get a lot of infections, which may be difficult to get rid of.

When too many white blood cells are made, they take up much more room in the bone marrow than they would normally. This means that there is not enough space for making normal red blood cells and platelets. Red blood cells carry oxygen round the body. If you don't have enough of these, you have anaemia. This can make you tired and breathless.

Platelets are vital for normal blood clotting. If you do not have enough platelets, you will have bleeding problems such as nosebleeds, very heavy periods or a fine rash of red spots caused by bleeding into the skin (petechiae).

Blood cells normally die when they are worn out. In some types of chronic leukaemia the blood cells are not over produced but they don't die when they are worn out. So, there are too many white blood cells than is normal.

There is information about the white blood cells, red blood cells and platelets and what they each do on the blood and circulation page.

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Updated: 26 February 2015