Lymphocytes are a type of white blood cell that play an essential role in the immune system, helping the body fight infections. A high lymphocyte count, also known as lymphocytosis, means having a higher-than-normal amount of lymphocytes in the blood. A temporarily high lymphocyte count usually means that the body is working as it should to protect against germs that cause infections. However, a high lymphocyte count can also be a sign of a more serious condition, such as a blood cancer or a chronic infection. Some common causes of high lymphocyte count include:
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Infections: Viral, bacterial, and parasitic infections can cause lymphocytosis.
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Autoimmune diseases: Chronic swelling and inflammation caused by autoimmune diseases can lead to lymphocytosis.
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Blood cancers: Lymphocytosis can be a sign of blood cancers such as leukemia and lymphoma.
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Other conditions: Other conditions that can cause lymphocytosis include underactive thyroid, tuberculosis, and HIV or AIDS.
It is important to note that a high lymphocyte count on its own is not necessarily problematic, especially in people with chronic lymphocytic leukemia (CLL). However, significant changes in lymphocyte count should be discussed with a healthcare provider to investigate further. If a high lymphocyte count is caused by an underlying condition, treatment of that condition can help bring the lymphocyte count back to normal.
