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Total number of T-lymphocytes (CD3) in the blood
Medical expert of the article
Last reviewed: 05.07.2025
Normally, the relative total number of T-lymphocytes in the blood of adults is 58-76%, the absolute number is 1.1-1.7×10 9 /l.
Mature T-lymphocytes are responsible for cellular immunity reactions and perform immunological surveillance of antigen homeostasis in the body. They are formed in the bone marrow and differentiate in the thymus gland, where they are divided into effector (killer T-lymphocytes, delayed-type hypersensitivity T-lymphocytes) and regulatory (helper T-lymphocytes, suppressor T-lymphocytes) cells. Accordingly, T-lymphocytes perform two important functions in the body: effector and regulatory. The effector function of T-lymphocytes is specific cytotoxicity in relation to foreign cells. The regulatory function (T-helper-T-suppressor system) consists in controlling the intensity of the development of a specific reaction of the immune system to foreign antigens. The regulatory effects of T-lymphocytes on cells of the monocyte-macrophage series are varied. The ability of T-lymphocytes to synthesize and produce cytokines will allow them to participate not only in the regulation of immune functions, but also in many vital processes. Many diseases are based on T-lymphocyte pathology, which in some cases is directly related to their damage, and in others is mediated through a violation of immune regulation.