CD3 Absolute Count Unit Converter

CD3 absolute count measures the total number of T lymphocytes circulating in your blood. CD3 is a protein complex found on the surface of all mature T cells, making it a reliable marker for identifying and counting them.

T cells are a central part of the adaptive immune system. They include CD4+ helper T cells, which coordinate immune responses, and CD8+ cytotoxic T cells, which directly destroy infected or abnormal cells. Because CD3 is present on both subtypes, this test captures the full T-cell population.

Typically 55-84% of lymphocytes are CD3+. The absolute count (cells per microliter) is more clinically useful than the percentage, because shifts in other lymphocyte populations like B cells or NK cells can make the percentage appear falsely abnormal even when T-cell numbers are unchanged.

T cells originate from stem cells in the bone marrow. Precursor cells migrate to the thymus, where they mature and acquire the CD3 marker before entering the bloodstream. The thymus is most active during childhood and gradually shrinks with age, contributing to the natural decline in T-cell production in older adults.