Lymphocytes (lymphs) are an important part of the immune system and play an active role in combating acute viral and chronic bacterial infections . There are two types of lymphocytes, T cells and B cells. The differential count does not identify or enumerate the number of T and B cells.
Normal Range (Adult) Lymphocytes 20-40% of all white cells.
An increase in the number of lymphocytes is called lymphocytosis and is seen in a variety of diseases. Viral diseases such as rubella, measles, mumps, viral respiratory infections, atypical pneumonia, infectious hepatitis, and infectious mononucleosis exhibit lymphocytosis. Bacterial infections such as syphilis and pertussis can also cause lymphocytosis. Malignant causes of lymphocytosis are lymphocytic leukemia and lymphoma. A decrease in lymphocytes is called lymphocytopenia and is seen primarily when the immune system is suppressed as in diseases such as AIDS and systemic lupus erythematosus.