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Causes of high and low T-lymphocyte counts
Medical expert of the article
Last reviewed: 06.07.2025
A decrease in the absolute number of T-lymphocytes in the blood indicates a deficiency of cellular immunity, while an increase indicates hyperactivity of the immune system and the presence of immunoproliferative diseases.
The development of any inflammatory process is accompanied by a decrease in the content of T-lymphocytes almost throughout its entire duration. This is observed in inflammations of the most diverse etiology: various infections, non-specific inflammatory processes, destruction of damaged tissues and cells after surgery, trauma, burns, heart attacks, destruction of malignant tumor cells, etc. The degree of decrease in the number of T-lymphocytes generally depends on the intensity of the inflammatory process, although such a pattern is not always observed. An increase in the number of T-lymphocytes in the dynamics of the inflammatory process is considered a favorable sign, but a high content of T-lymphocytes with pronounced clinical manifestations, on the contrary, is an unfavorable sign indicating a tendency to chronicity. Complete completion of the inflammatory process is accompanied by normalization of the number of T-lymphocytes. An increase in the relative number of T-lymphocytes is not of great clinical significance, but an increase in the absolute number of T-lymphocytes in the blood is very important for diagnosing leukemia.
Diseases and conditions that lead to changes in the number of T-lymphocytes (CD3) in the blood
Increase in the indicator |
Decrease in the indicator |
Hyperactivity of the immune system Acute and chronic lymphocytic leukemia Sezary syndrome |
Congenital defects of the immune system (primary immunodeficiency states) Acquired secondary immunodeficiency states:
T-cell lymphoma Hairy cell leukemia |