The absolute lymphocyte value is the number of lymphocytes contained per liter of blood, counted under a microscope. Normally, the absolute lymphocyte value is 1.1-3.2 x 10^9 cells/L. The percentage rate of lymphocytes is routinely tested in clinical laboratory tests and fluid sampling, and the normal value is 20%-40%. The leukocyte system is composed of neutrophils, lymphocytes, monocytes, eosinophils and basophils in the peripheral circulating blood, of which lymphocytes are the main type. An increase in the absolute lymphocyte value and lymphocyte ratio often indicates that the patient may have a combination of viral cell infection, while at the same time a decrease in the absolute lymphocyte value and lymphocyte ratio often represents the presence of an increase in the absolute neutrophil value and a combination of bacterial infection.