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Helper T-lymphocytes (CD4) in blood
Medical expert of the article
Last reviewed: 05.07.2025
Normally, the relative number of T-helper lymphocytes in the blood of adults is 36-55%, the absolute number is 0.4-1.1×10 9 /l.
T-helper lymphocytes are inducers of the immune response, regulate the strength of the immune response to a foreign antigen and control the constancy of the internal environment of the body (antigen homeostasis). An increase in the number of T-helper lymphocytes indicates hyperactivity of the immune system, a decrease indicates immunological insufficiency.
The ratio of T-helpers and T-suppressors in the peripheral blood is of primary importance in assessing the state of the immune system, since the intensity of the immune response depends on it. Normally, cytotoxic cells and antibodies should be produced in quantities that are necessary to remove a particular antigen.