Leukocytes can be divided into 5 types: neutrophils, eosinophils, basophils, lymphocytes and monocytes. The lymphocyte percentage is the percentage of cells of that form in the total white blood cell count. The lymphocyte ratio in normal physiological conditions is: 20% to 40%.
A low lymphocyte ratio is mainly due to a decrease in the absolute number of lymphocytes. Examples include the application of adrenocorticotropic hormones, alkylating agents, anti-lymphocyte globulin and other treatments, as well as radiation injury, immunodeficiency diseases, and gammaglobulin deficiency. In other cases, the number of other cells increases, such as leukemia and severe bacterial infections, and the number of neutrophils increases dramatically and the lymphocyte ratio decreases relatively.
High lymphocyte ratios are mainly seen in infectious diseases and mainly viral infections, such as: infectious mononucleosis, measles, chickenpox, mumps, viral hepatitis, epidemic hemorrhagic fever, but also in whooping cough, tuberculosis, brucellosis and syphilis. The number of lymphocytes increases in these conditions and the percentage increases. In addition, lymphoma and lymphocytic leukemia, recovery from acute infectious diseases, and after organ transplantation can also cause an increase in lymphocytes. There are also conditions that cause a decrease in the number of other cells and a relative increase in the proportion of lymphocytes, such as aplastic anemia.
Therefore, measuring the lymphocyte ratio can help to understand the immune function status of the body and judge the disease development. However, there are many causes of lymphocyte ratio changes, and the significance of lymphocyte ratio in blood routine alone is much less than the absolute value of lymphocytes for disease diagnosis, so it can only be used for initial screening.