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Lymphocytes are a type of white blood cell and are part of your immune system. A high level can point to a reaction to bacteria or viruses or to inflammation, and a low level can point to a condition of the bone marrow or the immune system, or be caused by certain medicines.[1]
On this page you can read what lymphocytes are, what the guidelines say about a value that is too low or too high, what affects your value and which values are best to look at alongside it.
Also known as: lymphocytes in the white blood cell differential, B cells and T cells. At the lab: GBBX.
Lymphocytes are one of the five types of white blood cells. White blood cells are also called leukocytes. They are made in your bone marrow and are found in your blood and in your lymphatic tissue, which is part of your lymphatic system.[1]
Lymphocytes come in two main types: B cells and T cells. B cells target viruses, bacteria and toxins that enter your body. Some T cells can clear away your body's own cells, for example cells affected by a virus.[1]
The test is also called a blood count with differential or a white blood cell differential. A separate test measures the total number of white blood cells in your blood.[1]
White blood cells are an important part of your immune system. When you are ill or your body is damaged, they travel through your blood and tissues to where they are needed. There they help your body defend itself.[1]
The five types of white blood cells do different work. Measuring them separately gives your doctor important information about your health.[1]
Your doctor can use the test to keep an eye on your health, to look for the cause of your symptoms or to follow how a value changes during care for a condition of the blood.[1]
One reason for the test can be that you feel unusually tired or weak, or that you have bruises with no clear cause.[1]
Labplusarts, the lab BioProfile works with, measures lymphocytes as a count per litre of blood, in 10^9/l. A widely used handbook for doctors gives 1.5 to 4.0 10^9/l as the usual range for adults. Your own result shows the range the lab uses for your test.[2]
| Value | What it means | Who it is for |
|---|---|---|
| 1.5 to 4.0 10^9/l[2] | Usual range | Adults |
Source: Harrison's Principles of Internal Medicine, normal white blood cell values in adults.[2]
| Value | What it can mean | Who it is for |
|---|---|---|
| Higher than normal[1] | Can point to a reaction to bacteria or viruses, or to inflammation | People whose blood count is being checked |
| Higher than normal[1] | Can point to a condition in which the immune system attacks the body's own cells, or to a condition of the blood or the lymphatic system | People with symptoms such as unusual tiredness or bruising |
| Higher than normal[1] | Can be caused by certain medicines containing a steroid, or by a reaction of your immune system to a substance from outside | People who take medication |
| Lower than normal[1] | Can point to a condition of the bone marrow or the immune system | People whose blood count is being checked |
| Lower than normal[1] | Can be caused by certain medicines, such as medicines against bacteria, or by medicines given as part of care for a serious condition | People who take medication |
| Higher or lower than normal[1] | Not always linked to a condition that needs medical care; smoking, alcohol, severe stress or damage to the body play a part | Everyone who takes the test |
MedlinePlus, U.S. National Library of Medicine, Blood Differential: what a higher or lower result can mean in people having a white blood cell differential. The source does not give its own limits for each type of white blood cell.[1]
A low number of white blood cells is called leukopenia. It can point to a condition of the bone marrow or the immune system. Certain medicines can also lower the level, such as medicines against bacteria and medicines given as part of care for a serious condition. If your result looks abnormal, your doctor can order extra tests to look for the cause.[1]
A high number of white blood cells is called leukocytosis. It can point to a reaction to bacteria or viruses, to inflammation, to a condition in which the immune system attacks the body's own cells, or to a condition of the blood or the lymphatic system. A reaction of your immune system to a substance from outside and certain medicines containing a steroid can also raise the level.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
When you are ill or your body is damaged, white blood cells go to the place where they are needed. A reaction to bacteria or viruses and inflammation can raise the number of white blood cells.[1]
Certain medicines containing a steroid can raise the number of white blood cells. Medicines against bacteria and medicines given as part of care for a serious condition can lower the number.[1]
Smoking and drinking alcohol can change your result. So an abnormal result does not always point to a condition that needs medical care.[1]
Severe stress and damage to the body can change your result. That is why your doctor also looks at your symptoms, your medical history and the results of other blood tests.[1]
Lymphocytes are included in all five packages, from BioProfile 31 to BioProfile 150.[3]
The BioProfile editorial team wrote this page on 30 September 2026 from the sources below, which we read on 30 September 2026. Every number on this page appears in one of those sources, with the number of that source next to it. An expert still has to review this page; after that review, the name of that expert and the date of the review appear at the top. This page gives an explanation, not a diagnosis. Discuss an abnormal value with your GP.
