Lymphocytes are produced by lymphoid organs and are an important cellular component of the body’s immune response function with the role of producing and transporting antibodies and defending against viral infections.
Normal reference value of lymphocytes: adults (0.8-4) × 10*9/L. The number of lymphocytes is influenced by both physiological and pathological factors.
Absolute reduction of lymphocytes is common for the following reasons: lymphocyte reduction during recovery from influenza; HIV infection, which selectively destroys CD4+ cells leading to a significant reduction in CD4+ cells and an inverted CD4+/CD8+ ratio; tuberculosis, where early lymphocytopenia CD4+ cells are significantly reduced and lymphocytes can return to normal if treatment is effective; alkylating agents (cyclophosphamide etc.) can cause a significant decrease in leukocytes, accompanied by a significant decrease in lymphocytes, and the decrease in lymphocytes can persist for several years after stopping treatment; radiation therapy can destroy lymphocytes, with each low-dose radiation therapy producing more destruction than 2 high-dose radiation therapies per week; immune diseases such as systemic lupus erythematosus, rheumatoid arthritis, mixed connective tissue disease, and polymyositis, due to antibodies producing anti-lymphocyte antibodies, resulting in Lymphocyte destruction and reduction, and the degree of reduction correlates with the titer of the antibody; congenital immunodeficiencies, such as various types of severe combined immunodeficiency, ataxia capillaris, malnutrition, or zinc deficiency, can cause lymphocytopenia to varying degrees. Certain drugs can also cause lymphopenia, such as menadione, nitrogen mustard phenylbutyrate, cortisone, epinephrine, lithium, nicotinic acid, steroids, etc.
Absolute lymphocyte increase is divided into physiological and pathological conditions: physiological lymphocyte increase includes higher lymphocytes in the afternoon and evening than in the morning, and up to 50% or more in infants 1 week after birth, which can last for 6-7 years and then gradually decrease to adult levels. Pathological increase in lymphocytes is commonly caused by: infectious diseases (recovery from typical acute bacterial infections, acute infectious diseases caused by certain viruses, recovery or chronic phase of certain chronic infections such as tuberculosis); neoplastic diseases (predominantly primitive and naive lymphocytosis: acute lymphocytic leukemia, acute transformation of chronic lymphocytic leukemia; predominantly mature lymphocytosis: chronic lymphocytic leukemia, lymphocytic lymphoma); post-transplantation of tissues (an increase in the absolute value of the lymph count in the pre-rejection period can be used as one of the indicators for monitoring the rejection of tissue and organ transplants); certain hematological diseases (aplastic anemia, granulocytopenia and granulocyte deficiency are relative increases in lymphocytes); drugs (aspirin, levodopa, phenobarbital etc.).
Therefore, by observing changes in the number of lymphocytes, it helps to understand the state of the body’s immune function, but there are many factors affecting the increase and decrease of lymphocytes, so it is difficult to confirm the diagnosis with this indicator alone, and other tests are still needed.