The bone marrow

All your blood cells are made from special cells called stem cells. The bone marrow gives the stem cells a safe place to divide and grow to form fully developed (mature) red cells, platelets and white cells.

These are then released into your blood to carry out different functions:

• Red blood cells contain haemoglobin, which carries oxygen from your lungs to all the cells in your body.
• White blood cells fight and prevent infection. There are several types of white cell. The two most important types are neutrophils and lymphocytes.
• Platelets are very small cells that help the blood to clot and prevent bleeding and bruising.

The levels of these cells in your blood are measured in a blood test called a full blood count (FBC). The figures below are a guide to the levels usually found in a healthy person.

Type of blood cell	Levels found in a healthy person
Haemoglobin (Hb)	13–18g/dl (men) 11.5–16.5g/dl (women)
Platelets	150–400 x 109/l
White cells (WBC)	4.0–11.0 x 109/l
Neutrophils	2.0–7.5 x 109/l
Lymphocytes	1.5–4.5 x 109/l

 

These figures can vary from hospital to hospital. Your doctor or nurse will be able to tell you what levels they use. They can also be slightly different in people of African-Caribbean and Middle Eastern origin.

The figures might look complicated when they’re written down, but in practice they are used in a straightforward way. For example, you’ll hear doctors or nurses saying things like ‘your haemoglobin is 14’ or ‘your neutrophils are 4’. Many people with CLL soon get used to these figures and what they mean.

Lymphocytes

People with CLL make too many lymphocytes, which are a type of white blood cell. Normally, they’re an important part of the body’s defence against bugs such as bacteria, fungal infection and viruses. They fight infections in several ways:

• they kill bugs directly
• they make special proteins called antibodies that stick to bugs and make it easier for other white blood cells to find and kill them
• they remember and recognise bugs – lymphocytes can live for a very long time so they can mobilise quickly to fight any infection you’ve had before.

Lymphocytes travel around in the blood and in the lymphatic system.

The lymphatic system is part of the body’s defence against infection. It’s made up of a network of lymph nodes (sometimes called lymph glands) throughout the body, connected by very fine tubes called lymphatic vessels. Lymphocytes travel through the lymphatic vessels in fluid called lymph.

Lymph nodes can be felt in the neck, armpit and groin. There are also lymph nodes in the chest and the tummy (abdomen). The tonsils (glands at the back of the throat), thymus and spleen (an organ on the left side of the tummy underneath the ribs) are also part of the lymphatic system.