Immunomodulation, T-Cell Activation & Antiviral Research
Thymosin Alpha-1 (Tα1, also known as Thymalfasin) is a 28-amino acid peptide naturally derived from the thymic hormone Prothymosin Alpha. One of the most extensively studied immunomodulatory peptides, it has been approved in over 35 countries (under the brand name Zadaxin) for treatment of hepatitis B, hepatitis C, and as an immune adjuvant in cancer and HIV therapy. Research documents potent effects on T-cell maturation, NK cell activity, dendritic cell function, and cytokine regulation.
Thymosin Alpha-1 is a 28-amino acid peptide (Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH) originally isolated from bovine thymosin fraction 5 by Allan Goldstein in 1977. It is the active component of the thymic hormone responsible for T-lymphocyte maturation and immunological competence.
Tα1 has been approved in over 35 countries for treatment of chronic hepatitis B and C, malignant melanoma, hepatocellular carcinoma, and as an immune adjuvant. It represents one of the few peptides with a substantial body of clinical (not just pre-clinical) evidence, with hundreds of clinical trials across multiple disease states. The research community continues to study its applications in infectious disease, cancer immunotherapy, and immune senescence.
Tα1 acts on immature thymocytes to promote their differentiation into mature T-lymphocytes (CD4+ helper and CD8+ cytotoxic cells). It binds to and activates toll-like receptor 9 (TLR9) on dendritic cells and T-cells, triggering downstream signalling through MyD88 and NF-κB pathways. This drives increased expression of T-cell surface markers (CD3, CD4, CD8) and promotes migration to peripheral lymphoid organs.
Tα1 promotes a Th1-dominant immune response, increasing production of IFN-γ, IL-2, and IL-12 while modulating Th2 cytokines. This shift toward Th1 immunity is relevant to antiviral and anti-tumour research, as Th1 responses drive cell-mediated immunity. In sepsis models, Tα1 paradoxically shows immunorestorative effects, counteracting the immunoparalysis that characterises late sepsis.
Beyond T-cells, Tα1 activates plasmacytoid dendritic cells (pDCs) — key innate immune cells — through TLR9, driving type I interferon production. It also enhances NK cell cytotoxicity, contributing to anti-viral and anti-tumour responses through innate immunity pathways independently of adaptive T-cell responses.
Mutchnick MG et al. conducted a placebo-controlled clinical trial in chronic hepatitis B patients, demonstrating that Tα1 treatment produced sustained HBeAg seroconversion in 16% of patients vs. 0% for placebo, with significant improvements in liver histology and viral load.
Romani L et al. demonstrated that Thymosin Alpha-1 directly activates plasmacytoid dendritic cells through TLR9 signalling, driving substantial type I interferon production. This innate immune activation mechanism provides a rationale for Tα1's antiviral activity independent of adaptive immunity.
Wu J et al. conducted a randomised study in ICU patients with sepsis showing that Tα1 treatment significantly reduced 28-day mortality (26% vs. 35% in controls), with restoration of T-cell counts and HLA-DR expression on monocytes as proposed mechanisms.
Garaci E et al. reviewed clinical evidence for Tα1 in cancer, demonstrating that adjuvant Tα1 treatment in lung, hepatocellular, and melanoma settings improved objective response rates and overall survival when combined with conventional therapies, through restoration of anti-tumour T-cell immunity.
Thymosin Alpha-1 reconstitutes in sterile water for injection or bacteriostatic water. Standard clinical preparations use 1.6 mg/ml. Our research vials (5mg and 10mg) reconstitute in 3–6ml BAC water as appropriate for research concentration needs.
The clinically approved dose of Thymosin Alpha-1 (Zadaxin) for hepatitis B/C is 1.6 mg subcutaneously twice weekly. Clinical trials in cancer and sepsis have used similar doses (1–3 mg per administration). Rodent research employs weight-based dosing of 100–500 mcg/kg. These are for scientific reference only.
| Product Name | Thymosin Alpha-1 (Thymalfasin / Zadaxin active component) |
| CAS Number | 62304-98-7 |
| Molecular Formula | C₁₂₉H₂₁₅N₃₃O₅₅ |
| Molecular Weight | 3,108.3 Da |
| Amino Acids | 28 (N-terminally acetylated) |
| Appearance | White lyophilized powder |
| Purity | ≥99% (HPLC) |
| Storage (lyophilized) | −20°C, protected from light |
| Storage (reconstituted) | 2–8°C, use within 14 days |
| COA | Available with each order |
