what causes lymphocytes
A high lymphocyte count, also referred to as lymphocytosis, can be caused by acute lymphocytic leukemia, chronic lymphocytic leukemia, cytomegalovirus (CMV) infection, human immunodeficiency virus (HIV), mononucleosis, multiple myeloma, tuberculosis, vasculitis, whooping cough and other viral infections.
A partial list of other causes for low lymphocyte count include medications (usually powerful anti-immune-system medicines or chemotherapy), autoimmune diseases such as lupus or rheumatoid arthritis, lymphoma and other cancers, and primary diseases of the immune system, such as aplastic anemia.
Your lymphocyte count is extremely low. There are many potential causes, some of which are serious. Infections are the most common cause. Any serious infection can temporarily reduce lymphocyte count, but most of these are acute, to the point that people need hospitalization. One common infection to cause a low lymphocyte count is HIV. In the early days of the epidemic, a low lymphocyte count was a clue to either acute or advanced HIV.