Lymphocytosis

Lymphocytosis, defined by an increase in absolute lymphocyte count (ALC) to more than 4000 lymphocytes/microL in adult patients, is a common hematologic abnormality. ALC calculates as the total white blood cell count (WBC) multiplied by the percentage of lymphocytes in the peripheral blood. Different lymphocyte subsets (T cells, B cells, or NK cells) may be increased depending on the particular etiology. Lymphocytes represent around 20 to 40% of WBC. The definition of relative lymphocytosis is an increase in WBC of more than 40% in the presence of a normal absolute white cell count. In this review, we present the most common causes in adult patients, in addition to a general approach to diagnosis and management of frequently encountered etiologies. 

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.

High lymphocyte blood levels often indicate your body is dealing with an infection or other inflammatory condition. A spike in your lymphocytes typically means that these white blood cells are springing into action to rid your body of an invader that can make you sick. Sometimes a serious condition, like cancers that affect your blood or lymphatic system, may cause elevated lymphocyte levels.

Many medical conditions can cause lymphocytosis.

Infections

Lymphocytosis often results from viral infections. Bacteria and parasites can also cause infection, resulting in a high lymphocyte count. Infectious causes of lymphocytosis include:

Epstein-Barr virus (the virus that causes mononucleosis).

Cytomegalovirus (CMV).

Influenza (the flu).

Whooping cough.

Adenovirus.

Hepatitis.

Chickenpox or shingles.

Mumps.

Rubella.

HIV.

Cancer

In some cases, lymphocytosis is one of the first signs of certain blood cancers (leukemia) or cancers of your lymphatic system (lymphoma). Cancers associated with lymphocytosis include:

Chronic lymphocytic leukemia.

Non-Hodgkin lymphoma.

Acute lymphoblastic leukemia.

Large granular lymphocyte leukemia.

Other causes

Smoking.

Allergic reaction to medicine.

Stress related to a medical emergency.

Some autoimmune diseases.

Asplenia (removal of your spleen).

Epstein-Barr virus (the virus that causes mononucleosis).

Cytomegalovirus (CMV).

Influenza (the flu).

Whooping cough.

Adenovirus.

Hepatitis.

Chickenpox or shingles.

Mumps.

Frequent infections. If you have chronic lymphocytic leukemia, you may experience frequent infections that can be serious. ...

A switch to a more aggressive form of cancer. ...

Increased risk of other cancers. ...

Immune system problems

Lymphocytosis isn't preventable. You can reduce your risk by taking steps to keep from getting sick:

Avoid physical contact with people who have a contagious bug.

Don’t share personal items with people who are sick.

Wash your hands frequently and thoroughly with soap and water.

Disinfect surfaces and commonly used items that may carry germs.