CD4-positive, CD8-positive T cell

CD4-positive, CD8-positive T cells (commonly known as *double-positive T cells*) are an intermediate maturation stage found in the thymus during the development of T lymphocytes. Immature thymocytes initially do not express CD4 or CD8 ("double negative"), but as they progress through development, they transiently express both markers, entering the double-positive (CD4+ CD8+) stage. This stage is critical for evaluating the functionality of the T cell receptor (TCR): only cells with competent TCR signaling proceed to mature into either CD4-positive (helper) or CD8-positive (cytotoxic) single-positive T cells. Double-positive cells are not a functional subset present in peripheral blood and are not recognized as unique therapeutic targets in clinical practice[4]. Note: - This name is likely incorrect or inappropriate as a therapeutic target; it references a population defined primarily by developmental immunology, not by established function, disease association, or drug targeting. Most immunology resources refer to CD4+ or CD8+ single-positive T cells as therapeutically relevant targets, not the double-positive stage[4]. - For clinically actionable or functionally relevant information, see entries for "CD4-positive T cell" (helper T cell, Th cell) and "CD8-positive T cell" (cytotoxic T lymphocyte, CTL)[1][2][3][5][6].

Other names

Double-positive T cellDP thymocyteCD4+ CD8+ T cell