Healthy Living

What Are Lymphocytes? Low, Normal, and High Lymphocyte Counts

Low, Normal, and High Lymphocyte Counts

Lymphocytes are a type of white blood cell produced in the bone marrow. A few lymphocytes enter the bloodstream while some move into the lymphatic system. Having a low or high lymphocyte count can help identify a person's medical condition. Normal lymphocyte counts usually vary from one laboratory to another. Moreover, adults and children do not have the same normal lymphocyte counts.

What are lymphocytes?

One of the important parts of the body is the white blood cells or WBCs. These blood cells help the body fight any type of bacteria, virus, antigens, or any toxins that can make a person ill. A weakened immune system is an indication that the amount of WBC in the body is reduced.

There are other types of white blood cells (WBCs) in our body, and one of them are called lymphocytes. All of the different types of white blood cells (WBCs) have unique functions, but they all work together when it comes to fighting diseases in our body.

How do lymphocytes work?

The bone marrow constantly produces blood cells including lymphocytes. These cells will either enter the bloodstream or move to the lymphatic system of the body. A group of tissues and organs such as the spleen, lymph nodes, and tonsils, is called as the lymphatic system, which protects the body from any kind of infection caused by parasites, bacteria, or viruses.

From the newly created lymphocytes cells, about 25 percent of these cells remain in the bone marrow and the rest of the 75 percent travel to the thymus and become T cells. These cells originate from the stem cells, which is in the bone marrow, and are similar in appearance. Most lymphocytes are short-lived with an average life span of a week to a couple of months. However, a few of the lymphocytes can exist for years.

The B cells attack any invading antigens by producing antibodies, whereas the T cells destroy the cells that have become cancerous.

The B cells and T cells are then split into two different kinds:

  • Memory cells – These cells have been in the body for a longer duration to recognize and remember any past infections, which have already affected the body, and get back into action the moment the body gets reinfected with the same antigens.
  • Effector cells – These cells are activated by the antigens to fight against any new or active infection that has affected the body.

Each lymphocyte bears receptors that can bind to specific antigens. They have the ability to respond to any type of antigen, each with a receptor capable of recognizing unique antigens.

What are the roles of B and T cells in the body?

B cells recognize foreign substances and produce antibodies to fight the antigens. The T cells present in the thymus multiply and differentiate. There are three main types of T cells, and each type has its own role to play. They are helper T cells, regulatory T cells, and cytotoxic T cells. These T cells are then sent to circulate in the blood or placed in the peripheral tissues. Diverse subsets of T lymphocytes influence blood pressure.

Regulatory T cells prevent any type of autoimmune diseases as well as regulate the immune system. Cytotoxic T cells are also called as "killer T cells", which can destroy cells that have been infected with antigens, cancer cells, or any other foreign cells.

Helper T cells often direct the response of B and T cells. The helper T cells secrete chemical messengers, which are also known as "cytokines" once they are stimulated by antigens. These cytokines stimulate the differentiation of B cells, thereby activating antibody production.

If the body shows signs of infection or a blood disorder, the doctor would suggest a blood test called as the "B and T cell screen". Most infections and other types of disorders show an abnormal lymphocyte count. The blood test will show the count of lymphocytes present in the bloodstream. If the count is too high or too low, it is a sign of an illness.

Blood is drawn from the body and is sent to the laboratory for testing. There are a few things that would affect the result of the blood tests. They include:

  • Any recent infection
  • If an individual had undergone chemotherapy or radiation therapy
  • Being HIV-positive
  • History of surgery
  • If you are pregnant or breastfeeding
  • Lifestyle changes
  • Stressful situations in life

Characteristics of Lymphocytes 

A normal-looking lymphocyte appears large with a dark-stained nucleus. In normal situations with the absence of infections, the coarse dense nucleus of a lymphocyte is approximately the size of a red blood cell (RBC). Other lymphocytes show a clear perinuclear zone or a halo around the nucleus.

At times, it becomes impossible to identify B and T cells. A cytometry test can be done to distinguish the specific population count of these cells. The test can help identify the percentage of lymphocytes if they contain a particular combination of a specific cell or cluster of differentiation.

Lymphocyte Functions

Lymphocytes are significantly involved in maintaining the body’s immune response mechanism through the development of humoral and cellular immunity.

  • Humoral immunity – involves how B cells recognize and respond to antigens. These B cells transform themselves into plasma cells, which later produce antibodies to act upon any type of antigen.
  • Cellular immunity – includes transplant rejection, which is a defense against intracellular organisms or against neoplasms. Cellular immunity uses T cells to get rid of antigens. The development and production of T cells depend on the thymus, which is why they are regarded as "T" cells.

The majority of T cells can live longer with an average span of 4-5 years, but can also survive for as long as 20 years. They are also known for leaving and then re-entering the circulation many times during their entire life span.

It is difficult to differentiate B and T cells through blood film viewing since they are almost identical. However, they can be identified through immune cell markers.

Normal Count of White Blood Cells (WBCs) and Lymphocytes

Lymphocytes are one of the components counted in a complete blood count (CBC) test. A CBC test includes white blood cell differentials. The test is used to determine, diagnose, or monitor various medical conditions in a person. The lymphocyte count may vary for both adults and children. The lymphocyte level can be analyzed in the blood tests. The values can be seen in a CBC result.

An adult should have a normal WBC range of 4,500-11,000 WBC/mcL or 4.5-11.0 x 109 per liter, which is 1 percent of the total volume of blood in the body. When it comes to the lymphocyte count, it should be in the range of 800-5,000 lymphocytes/mcL or 0.8-5.0 x 109 per liter, which is 18-45 percent of the total white blood cells (WBCs) present in the body.

When the WBC count starts depleting to fewer than 2,500 WBC/mcL, it is considered as leukocytopenia (low WBC count). On the other hand, when it starts increasing to more than 30,000 WBC/mcL, then it is called as leukocytosis (high WBC count), which is again, not a good sign. 

When it comes to the lymphocyte count, fewer than 800 lymphocytes/mcL is termed as lymphocytopenia (low lymphocyte count) and greater than 5,000 lymphocytes/mcL is regarded as lymphocytosis (high lymphocyte count) count in adults. In the case of children, the threshold varies per age. Children can go as high as 9,000 lymphocytes/mcL.

A percentage may also be given to you, which includes T-cells, B-cells, and natural killer (NK) cells. It should be between 15 and 40 percent of white blood cells.

It is important to remember that the normal values can vary from one laboratory to another. 

Lymphocytosis (High Lymphocyte Count)


There are many causes that can lead to a variation in an abnormal lymphocyte count, which may become life-threatening if not treated on time. Infections, chronic inflammation caused by autoimmune disorders, and cancer of the lymphatic system or blood are some of the common reasons for a high lymphocyte count.

A high lymphocyte count is called as lymphocytosis. The lymphocyte count tends to increase when there is an infection in the body. In most cases, a high lymphocyte count shouldn’t pose much of a threat since it is quite normal during and after suffering from an illness.

However, if there is a consistent high lymphocyte count, then it can be due to serious diseases that would need immediate medical attention. Such conditions include:

  • Hepatitis - it causes inflammation of the liver. Symptoms include abdominal swelling, pain, fatigue, and yellowing of the skin and eyes.
  • Being HIV-positive or AIDS - it damages the immune system. It can take many years for the person to develop AIDS from HIV. The body finds it difficult to fight against infections. The virus is transmitted by coming into contact with infected blood, having unprotected sex, from an infected mother to the baby, and through breastfeeding.
  • Viral infections - can also increase the count of lymphocytes during viral infections such as influenza, measles, infectious mononucleosis (mono), and adenovirus infections.
  • Vasculitis - in this condition, the blood vessels become inflamed, which causes changes in the walls of the blood vessels. The changes include scarring, weakening, thickening, or narrowing of the blood vessels. Vasculitis can be either acute or chronic.
  • Tuberculosis - it is a bacterial infection that may cause lymphocytosis. It affects the lungs and may also affect the central nervous system, genitourinary system, lymphatic system, circulatory system, as well as the bones and joints. It is one of the most deadly infectious diseases.
  • Whooping cough - respiratory illnesses like whooping cough and flu can increase the lymphocyte count. Symptoms of whooping cough include severe coughing, which is accompanied by a whooping noise. Medications of cough are usually not helpful. The doctor may prescribe antibiotics. Whooping cough can also be prevented through vaccinations. Flu causes respiratory distress, fever, and fatigue. In extreme cases, the condition can turn out to be deadly. Rest and increased intake of fluids are recommended. However, in some cases, antiviral medications are prescribed by the doctor.
  • Cytomegalovirus infection - the infection spreads through infected body fluids such as breast milk, semen, blood, saliva, and urine. However, people are rarely affected by CMV. An individual's risk of contracting CMV increases if he or she has a weak immune system or is pregnant. 
  • Acute lymphocytic leukemia (ALL) - it is the cancer of the bone marrow and blood. In this disease, immature blood cells are produced quickly, hence, the term "acute". In ALL, the lymphocyte count goes high. Other symptoms include frequent nosebleeds or infections, fever, bone pain, bleeding gums, and swollen lymph nodes that lead to lumps.
  • Chronic lymphocytic leukemia (CLL) - it is also a cancer of the bone marrow and blood. However, unlike ALL, this type of leukemia slowly progresses, which is why it is referred to as "chronic". In this disease, the white blood cells are affected. Symptoms include enlarged but painless lymph nodes, weight loss, fatigue, and frequent infections.
  • Multiple myeloma - it is a form of cancer that affects plasma cells. Some may experience symptoms such as a change in the RBC count, kidneys, the immune system, or the bones.
  • Crohn's disease - it is an autoimmune disease, wherein the digestive tract becomes chronically inflammed. Symptoms include weight loss, diarrhea, and abdominal pain.


The person may or may not experience any symptoms. However, in some cases, the patient would have the following symptoms:

  • Sore throat
  • Sudden increase or decrease in body temperature along with fever and general exhaustion
  • Fever
  • Fatigue
  • Night sweats
  • Infection
  • Loss of weight or appetite
  • Acne or Pimple mark
  • Enlargement of the spleen (may also cause stomach fullness)
  • Irregular breathing
  • Swollen lymph nodes in the neck, groin, or stomach
  • External signs such as infection of the nose, relatively low energy levels, or redness of the oral mucous membrane 
  • Nausea, constipation, diarrhea, and vomiting
  • Insomnia and general disorders of the nervous system
  • Increased performance of the bone marrow tissues
  • Symptoms of respiratory diseases

Types of Lymphocytosis

There are two types of lymphocytosis: polyclonal and monoclonal. In monoclonal lymphocytosis, the number of lymphocytes increases due to a defect in the lymphoid cell, whereas polyclonal lymphocytosis is usually caused by an infectious or inflammatory problem.

Identifying the cause of the condition plays an important role in the treatment of lymphocytosis. In severe cases, bone marrow transplantation and blood transfusion may be needed.

Natural Treatment of Lymphocytosis

  • Diet - consume unprocessed whole foods, where vegetable seeds, whole grains, and fruits are part of your staple diet. You also have to drink adequate amounts of fluid.
  • Reduce stress and tension - get involved in activities that encourage emotional balance, which relaxes your body’s systems and facilitates its smooth functioning.
  • Alternative therapies - acupuncture, bioenergetics, reflexology massage, and some medications may help.
  • The practice of a philosophy of life - Ayurveda or macrobiotics may help balance and reorganize your life.

Lymphocytopenia (Low Lymphocyte Count)


A low lymphocyte count is called as lymphocytopenia. This condition usually occurs if the body is not producing enough lymphocytes, if such cells are being destroyed, or if the lymphocytes are trapped in the lymph nodes or spleen.

Having a low lymphocyte count can be due to a number of diseases such as flu or any mild infection--those that are not serious, but at times, can put a person at a greater risk of developing other types of infections.

  • Chemotherapy or radiation therapy - cancer of the blood can cause a low lymphocyte count. The symptoms include lymphoma and leukemia. Radiation and chemotherapy are the only options available for treatment. However, they further cause the lymphocyte count to drop.
  • Lupus or any type of autoimmune condition - multiple sclerosis, lupus, and rheumatoid arthritis can cause a low lymphocyte count. Multiple sclerosis causes physical disability by destroying the protective covering of the nerves. Rheumatoid arthritis causes joint deformity by causing inflammation of the joints. Lupus leads to inflammation of the body's organs, which can be fatal. The doctor will provide treatment depending on the cause of lymphocytopenia.
  • Use of strong steroids - can lead to a low lymphocyte count. Drugs that treat arthritis and other conditions may reduce the lymphocyte count.
  • Aplastic anemia/bone marrow dysfunction - in this condition, the body is not able to produce adequate amounts of white blood cells. Symptoms include fatigue, vulnerability to uncontrolled bleeding, and infections. Treatment includes blood transfusion, observation, and medications. If the condition is severe, then bone marrow transplantation is advised.
  • Infectious diseases - these include tuberculosis, AIDS, and viral hepatitis. The HIV destroys the body’s immune system. Viral hepatitis, if left untreated, leads to cancer of the liver. Tuberculosis affects the lungs and if not treated early, may become fatal. By determining the right cause, the doctor can administer appropriate drugs, which include antibiotics, antiviral, antifungal, or antiparasitic medications.
  • Certain genetic disorders - these disorders can reduce cell growth, which also causes a decrease in the lymphocyte count. Such disorders include the Wiskott-Aldrich syndrome (WAS) and DiGeorge anomaly.

Other causes of lymphocytopenia:

  • Lymphoma or Hodgkin's lymphoma
  • Being HIV-positive or AIDS
  • Influenza virus
  • Malnutrition

People who have a low lymphocyte count may or may not experience any symptoms. At times, they may have fever or some other symptoms of an infection. Having a low lymphocyte count can be acute or chronic. When we say "acute", it means something that usually occurs for a short time and gets resolved later on. The term "chronic" means something that occurs for a longer period of time.

  • Acute lymphocytopenia - can be due to fasting, high levels of stress, certain viral infections, and the use of corticosteroids or therapy done during cancer.
  • Chronic lymphocytopenia - is caused by certain autoimmune diseases such as rheumatoid arthritis and lupus, any type of cancer, or certain chronic conditions such as AIDS and tuberculosis.


Symptoms may not show when there is mild lymphocytopenia. However, for some people, they may experience the following symptoms:

  • Small lymph nodes and tonsils due to an inherited immune system disorder
  • Fever and runny nose due to a viral infection
  • Enlarged spleen or lymph nodes suggesting the presence of cancer or HIV infection
  • Rashes
  • Swollen and painful joints
  • Cough, runny nose, and fever indicating a respiratory viral infection
  • Rashes and painful swollen joints suggesting rheumatoid arthritis or lupus


The diagnosis is usually done by carrying out a complete blood count (CBC). Usually, doctors suggest this test when a person has a recurrent or severe infection. When the number of lymphocytes is drastically reduced, doctors will suggest for other blood tests to identify other types of infection. When the lymphocyte count is very low, doctors usually do blood tests for human immunodeficiency virus (HIV) and other infections. At times, a sample of the bone marrow can also be taken for further microscopic examination.

A decrease in a certain type of lymphocyte would help the doctor come up with an accurate diagnosis. This will help the doctor diagnose some disorders such as certain hereditary immunodeficiency disorders or AIDS.

Treatment for Lymphocytopenia

The treatment depends on the cause. Once a diagnosis is established, the doctor would suggest a treatment plan based on the cause of the problem. If the cause of lymphocytopenia is due to an overdosage of a certain drug, then it can be resolved once the patient stops taking the drug.

If the cause of lymphocytopenia is due to AIDS, then there would be a certain therapy to increase the number of T-cells to increase the survival rate of the patient. Doctors would also recommend gamma globulin, which is rich in antibodies to prevent infections. It is also good for people with a low B-cell count.

In certain cases, a bone marrow or stem cell transplantation would be advised based on the seriousness of the disease. If a person has developed an infection, then a specific antibody, antifungal, antiviral, or antiparasitic drug is given against that infectious organism.