13598 IUPAC Gold Book - pre-T cell 10.1351/goldbook.13598 13598 current synonyms: single-positive cell, thymocyte 1 Cell differentiating into a T lymphocyte in the thymus gland. During maturation thymocytes express on their surface a precursor T-cell receptor (TCR) called a pre-T-cell receptor, and both CD8 and CD4 proteins (double-positive cells). At the same time they slowly migrate from the outer cortex of the thymus to the inner medullary region. Only the \(\pu{2\%}\) of cells capable of distinguishing self-antigen survive to maturity in the medulla. Here they become single-positive cells, expressing exclusively CD4 or CD8 surface proteins, and are exported from the thymus in the bloodstream to become helper T cells (Th) and cytotoxic T cells, respectively. CD4 https://goldbook.iupac.org/terms/view/12973 CD8 https://goldbook.iupac.org/terms/view/12976 T lymphocyte https://goldbook.iupac.org/terms/view/13724 T-cell receptor (TCR) https://goldbook.iupac.org/terms/view/13714 cytotoxic T cells https://goldbook.iupac.org/terms/view/13072 double-positive cells https://goldbook.iupac.org/terms/view/13102 helper T cells (Th) https://goldbook.iupac.org/terms/view/13199 self-antigen https://goldbook.iupac.org/terms/view/12914 PAC, 2012, 84, 1113. 'IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)' on page 1233 (https://doi.org/10.1351/PAC-REC-11-06-03) https://goldbook.iupac.org/terms/view/13598/html https://goldbook.iupac.org/terms/view/13598/json https://goldbook.iupac.org/terms/view/13598/plain Citation: 'pre-T cell' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.13598 The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org . The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using. 2026-06-30T10:17:06+00:00