HomeHealth A-ZLymphocytosis


Lymphocytes are white blood cells present in the body that help fight infections and other viruses entering the human body. These lymphocytes play an essential role in our body. In lymphocytosis, the number of lymphocytes in the blood goes above the normal range. 

The bone marrow of our body constantly produces lymphocyte cells. These lymphocytes go to the bloodstream, and some move to the lymphatic system. Sometimes, these lymphocyte cells increase in the blood and cause lymphocytosis.

The absolute blood count is also an important parameter while calculating the number of lymphocytes in the blood. It calculates the number of cells in absolute numbers rather than expressing it in the form of a percentage.

The Function of Lymphocyte

Lymphocytes are of three types – T cells, B cells, and NK cells. B lymphocyte cells are helpful for the formation of antibodies in the body. The T cells are used to kill cancer cells and also protect your body from foreign substances. The NK cells are natural killers. These cells are specialized in killing the virus cells as well as the cancer cells. The natural killer cells are specialized in targeting the infected cells. 


The normal range of lymphocytes varies from 800 to 5000 lymphocytes per ml of blood. It is mainly 18% to 45% of the White Blood Cells (WBC) count. The number of lymphocytes also varies according to the age of a person. Lymphocytosis is very common. It is common particularly in people who have:

  1. Had a recent infection (most commonly viral)
  2. A reaction to a new medication 
  3. A medical condition which causes long-lasting inflammation, such as arthritis
  4. Severe medical illness like trauma
  5. Some types of cancer, such as leukemia or lymphoma
  6. Had their spleen removed

There are multiple reasons for this disease. Specific causes of lymphocytosis include

Other viral infections

Symptoms of Lymphocytosis

There are usually no severe symptoms of lymphocytosis. If lymphocytosis is due to severe disease, there might be some symptoms. These symptoms are swelling in the lymph nodes in the neck region, armpits, and near your stomach. Other symptoms include shortness of breath, severe pain, fever, night sweats, loss of appetite, fatigue, infection, nausea, vomiting, etc.

Diagnosis of Lymphocytosis

Lymphocytosis is diagnosed by CBC (Complete Blood Count) blood test. CBC helps us determine the number of white blood cells in the blood and the lymphocytes present in the white blood cells.. Other procedures include bone marrow biopsy, which helps find the root cause of lymphocytosis. One of the important points that doctors might look into is your medical history and medications and conduct other examinations.

The diagnosis of lymphocytosis shows that you have or have earlier had an infection or illness. In most of the cases, lymphocytosis simply means that our body has been fighting a viral infection.

In few cases, lymphocytosis is one of the first signs of certain blood cancers, such as chronic lymphocytic leukemia (CLL) – the most common type of leukemia observed in adults. Further diagnostic tests are usually necessary to rule out other conditions and make a firm diagnosis of the cause of lymphocytosis.


The treatment of lymphocytosis involves the treatment of the  reason. Most cases of lymphocytosis are cured by treating the underlying disease, which can be the primary cause of the disease. 

Cancer can also cause lymphocytosis. In such cases, doctors advise chemotherapy. Generally, more than one drug is used, or a combination of drugs is used that target the affected cells. Chemotherapy is usually done in three- to four-week cycles. The duration may be extended, depending on the severity. The gap between weeks is to allow the cells to heal and repair. There might be some side effects like fever, nausea, low blood counts, etc.

Immunotherapy is another complex procedure to treat severe cases of lymphocytosis. In immunotherapy, the drugs are used to help your immune system identify the cells and destroy these cells.

Other forms of treatment include targeted cell therapy, stem cell therapy, etc. These treatments are generally used to treat severe cases of lymphocytosis.

When to Consult the Doctor?

If you have severe symptoms and the effects of this disease persist, you must consult a doctor. The doctor will guide you and ask you to undergo tests. If your Complete Blood Count report shows a high level of lymphocytes, it can indicate lymphocytosis. If you have a family history of such an illness, you must take extra care.


Lymphocytosis cannot be prevented entirely. There are only some ways through which its risk can be reduced.

  • Keeping a safe distance from an infected person and avoiding sharing your personal items with a sick person.
  • Disinfecting items of common use.
  • Cleaning your hands frequently with soap and water


The number of lymphocytes in the blood can vary significantly. The high number of lymphocytes may or may not cause  symptoms or signs. It is important to have a regulated number of lymphocytes in the white blood cells. Both higher and lower numbers can be harmful to the body. 

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