Conditions That Cause Lymphocytosis

Lymphocytosis is a term used to describe a condition in which an individual has a higher than normal amount of lymphocytes in their blood. Lymphocytes are white blood cells that fight off pathogens and reside in the lymphatic system. They do this by differentiating into memory cells to recognize pathogens the body has seen before and by differentiating into plasma cells that make antibodies to fight the pathogen off. While a high lymphocyte count is relatively normal following a recent infection, it is not normal for it to stay elevated. When the lymphocyte count exceeds three thousand lymphocytes in a microliter of blood, it is lymphocytosis.