A low number of lymphocytes can happen if you take certain medications or have an infection or health condition that affects the immune system. Treatment can depend on the cause.

Lymphocytopenia, also called lymphopenia, occurs when the lymphocyte count in your blood is lower than usual. Severe or chronic low counts can indicate a possible infection or other illness.

Lymphocytes are a kind of white blood cell. They’re part of your immune system. These essential cells circulate in blood and lymph fluid. They defend your body by attacking at the first sign of an invasion by harmful organisms. Lymphocytes also play a key role in triggering other immune actions and help build your body’s immunity through past infections and vaccinations.

Three main types of lymphocytes work together to help identify and eliminate infections and other diseases. They include:

  • B cells make antibodies and signaling proteins that help flag or attack invading bacteria, viruses, and toxins.
  • T cells communicate with B cells and seek and destroy the cells that have become infected or are cancerous.
  • Natural killer (NK) cells contain compounds that can kill cancer tumor cells and cells infected by a virus.

Low levels of T cells or too few NK cells can lead to uncontrolled viral, fungal, and parasitic infections. B-cell lymphocytopenia can lead to an increase in harmful and different types of infections.

Lymphocytopenia may indicate an underlying illness, condition, or another factor. You usually develop these causes rather than inherit them.

T cells make up the largest proportion of lymphocytes, and T-cell lymphocytopenia is the most common. However, this condition can affect all three cell types.

Causes can include:

Autoimmune disorders

Autoimmune disorders occur if the immune system is in overdrive and incorrectly attacks the body’s cells and tissues. These can include:

Certain immunosuppressant medications used to treat autoimmune disorders may cause lymphocytopenia.

Cancer and treatments for cancer

Cancer — especially blood or lymphatic cancers like lymphoma (such as Hodgkin’s lymphoma), Kaposi sarcoma, and leukemia — can result in low lymphocyte levels.

The following cancer treatments may also result in lymphocytopenia:

Diseases that affect the blood and bone marrow

These conditions can cause low lymphocyte levels:

Infections

Viral, bacterial, parasitic, and fungal infections can cause lymphocytopenia. Any type of infection may cause your lymphocyte count to fall. For example:

Lymphocytopenia may be a predictor of sepsis or acute bacteremia. Sepsis is a severe infection that causes systemic inflammation, and acute bacteremia is a bacterial presence in the blood that could lead to sepsis. Both require urgent medical attention.

Inherited causes

Inherited or congenital causes of lymphocytopenia are rare. Some of these include:

  • ataxia-telangiectasia
  • DiGeorge syndrome
  • severe combined immunodeficiency
  • common variable immunodeficiency
  • Wiskott-Aldrich syndrome

Nutritional causes

Malnutrition or undernutrition can cause lymphocytopenia. This occurs when the body lacks protein and other nutrients necessary to produce lymphocytes.

An eating disorder, such as anorexia nervosa, may lead to reduced-production lymphocytopenia.

Gastrointestinal conditions

Conditions that damage the gut wall can affect the body’s absorption of nutrients and may lead to lymphocytopenia in some cases. These are generally referred to as protein-losing enteropathy and include:

A deficiency of the mineral zinc in your diet can weaken immune health by affecting T lymphocytes. This may contribute to lymphocytopenia and other immune system dysfunctions.

Medications

In addition to cancer treatments, several other drugs can reduce lymphocytes. Medication-induced lymphocytopenia ranges from minor to severe.

Medications that may lower your lymphocyte level can include:

  • azathioprine (Imuran, Azasan)
  • carbamazepine (Tegretol, Epitol)
  • cimetidine (Tagamet)
  • corticosteroids
  • dimethyl fumarate (Tecfidera)
  • imidazoles
  • interferons
  • methotrexate (Trexall, Rasuvo)
  • opioids
  • certain bisphosphonate therapy for osteoporosis

Kidney disease

Kidney disease, particularly late stage chronic disease, can reduce the number of T cells in the blood. But lymphocytopenia can also occur in acute kidney injury.

Trauma and surgery

Trauma from an injury or acute emergency, such as cardiac failure, can lower lymphocyte counts. Undergoing surgeries such as cardiac bypass can also cause lymphocytopenia.

Other causes

Other causes of lymphocytopenia include stress and alcohol misuse.

Additionally, there is a rare condition known as idiopathic CD4 lymphocytopenia, in which the cause is unknown.

You may be at risk of lymphocytopenia if:

  • you’ve had a recent infection or surgery
  • you have an underlying condition that can cause lymphocytopenia
  • you’re taking any medications that may affect your lymphocyte count

Older adults and those who are malnourished are particularly at risk.

You may not notice any symptoms of lymphocytopenia. Sometimes, you may experience symptoms of the underlying cause or condition. For example:

A complete blood count (CBC) with differential can determine your lymphocyte level. A doctor may also recommend a blood test called a lymphocyte profile, also known as a lymphocyte subset panel, to determine the counts of T, B, and NK cells in the body.

A diagnosis of lymphocytopenia means that your blood lymphocyte count is below 1,500 cells/microliter.

Infants and children typically have more lymphocytes. Fewer than 2,000 cells/microliter is too low for children under 6.

Treatment depends on the cause, and treating the underlying factor usually resolves lymphocytopenia. You may also require therapy to prevent infections or other complications due to a compromised immune system.

If a medication is causing low counts, a doctor may stop or change the medication. Drug-related lymphocytopenia usually clears up after a person stops taking the medication.

For other causes, your doctor may prescribe the following medications:

  • antiretroviral combination therapy for HIV
  • other antiviral agents, antibiotics, antifungals, or antiparasitic drugs to treat specific infections
  • gamma globulin to help prevent infections that can occur due to B-cell lymphocytopenia
  • bone marrow stem cell transplant for some cancers affecting the blood and bone marrow

Lymphocytopenia is a common diagnosis from a complete blood count test.

Some people may have values slightly less than the usual range without any reason. Low counts are also common in older adults with no concerning symptoms.

This condition may reflect illness, recent surgery, or drug therapy and is usually reversible.

A doctor typically looks over your current and previous medical history to see if the lymphocytopenia is a new condition. Most cases resolve spontaneously without medical care.

If you receive a diagnosis of acute lymphocytopenia, a doctor will carefully monitor your levels with follow-up blood tests. You may need further tests and treatment to address the main cause. This may involve:

  • specialist referrals
  • additional blood tests
  • imaging
  • bone marrow biopsy

Lymphocytopenia may indicate or lead to serious illness that can potentially be fatal. Treatment and careful attention to your health are necessary to rebuild your weakened immune system and help you stay healthy.

You may not be able to prevent lymphocytopenia, but you can help boost your immune system and protect yourself against infections. This can include:

  • following a healthy diet plan that’s rich in nutrients to provide energy
  • getting plenty of rest
  • avoiding germs and delaying visits with people who are not feeling well
  • washing your hands thoroughly with warm, soapy water several times a day to help prevent illness
  • using hand sanitizer if you’re out
  • avoiding crowded areas
  • avoiding injury, such as scrapes, cuts, or nicks on your skin
  • having someone else clean up after pets

A nutritionist can help you choose whole foods that are right for you and are packed with protein, healing minerals, and vitamins.

A doctor may also prescribe a specific diet if you have a weakened immune system. This may include:

  • avoiding raw foods, including fruits and vegetables
  • not eating foods past their expiration date
  • heating and reheating foods to the proper temperatures
  • thoroughly cleaning and sanitizing surfaces and utensils to avoid contamination

What does it mean if your lymphocytes are low?

A low level of lymphocytes can happen if you have recently had an infection. It can also occur with certain health conditions, such as autoimmune diseases and cancers affecting the immune system, and while using certain medications.

How do you fix low lymphocytes?

There isn’t a specific way to increase your lymphocyte level. If you have a low lymphocyte count, doctors may need to treat the underlying cause. Sometimes, a low lymphocyte count can happen without a reason. Depending on your levels, a doctor may recommend taking precautions to avoid infection, getting enough sleep, and eating a nutritious diet until your body produces more lymphocytes.

What is an alarming lymphocyte count?

You may have lymphocytopenia if your blood lymphocyte count is below 1,500 cells/microliter. In children under 6 and infants, fewer than 2,000 cells/microliter may indicate lymphocytopenia.

Lymphocytopenia happens when you have a low number of lymphocytes, a type of white blood cell.

In some cases, lymphocytopenia can increase your risk of severe infections.

Treating it typically involves treating the underlying cause.