Detailed Explanation
Thymosin alpha-1 (Tα1) is a 28-amino-acid peptide originally isolated from thymus gland extracts (thymosin fraction 5) by Allan Goldstein's laboratory at George Washington University in 1972. It is N-terminally acetylated and has the sequence Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN. Tα1 functions as an immune modulator, enhancing both innate and adaptive immune responses.
Thymosin alpha-1 acts on dendritic cells and T-cells to promote immune surveillance. It stimulates dendritic cell maturation and antigen presentation, enhances T-cell differentiation and activation (particularly Th1 responses), increases natural killer cell activity, and modulates cytokine production. Unlike immunosuppressants, Tα1 doesn't suppress the immune system — it restores and balances immune function, which is why it is sometimes called an immune 'rebalancer' rather than a stimulant.
A synthetic version of Tα1, marketed as Zadaxin (thymalfasin), is approved in over 35 countries (primarily in Asia, South America, and parts of Europe, but not the United States) for the treatment of chronic hepatitis B, hepatitis C, and as an immune adjuvant. It has been used as an adjunct therapy in various cancers and studied during COVID-19 for its potential to support immune recovery in immunocompromised patients. The peptide has a half-life of approximately 2 hours after subcutaneous injection.
Key Facts
- 28-amino-acid N-terminally acetylated peptide from the thymus
- Enhances dendritic cell maturation and T-cell function
- Approved as Zadaxin (thymalfasin) in 35+ countries — not FDA-approved in the US
- Indications: chronic hepatitis B, hepatitis C, immune adjuvant in cancer
- Half-life: ~2 hours after subcutaneous injection
- Immune modulator — restores balance rather than broadly stimulating
- Studied as COVID-19 adjunct therapy for immunocompromised patients
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