If you have been reading about clinical endpoint and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-03-29. Numbers and descriptions here follow the published literature rather than marketing material.
Lyophilized thymosin alpha-1 is generally stored at or below minus twenty degrees Celsius, protected from moisture and light. Short-term handling at ambient temperature is possible for dry powder, but reconstituted solutions degrade faster and are usually kept at two to eight degrees Celsius with a defined expiry of days rather than weeks. Repeated freeze-thaw cycles should be avoided because they promote aggregation and loss of potency. Exact limits depend on the formulation and should follow the supplier's documentation.
Identity and purity are normally assessed by reversed-phase high-performance liquid chromatography, which separates the peptide from related impurities and truncation products. Mass spectrometry confirms molecular mass and detects modifications such as deamidation or oxidation. Amino acid analysis and peptide mapping provide additional sequence-level confirmation. For research material, a certificate of analysis typically reports these results together with water content and counter-ion identity, since the lyophilized powder is often supplied as an acetate or trifluoroacetate salt.
Thymosin alpha 1 was identified in 1977 as a component of thymosin fraction 5, a heterogeneous preparation used in early studies of thymic function. Investigators purified the active material and determined its amino acid sequence, which enabled chemical synthesis. Work in the following decades concentrated on T-cell maturation and immune reconstitution in animals and small human cohorts. Early preparations varied in composition, so results from that period are difficult to compare with studies using defined synthetic peptide.
Clinical research has examined the peptide in chronic hepatitis B and C, as a vaccine adjuvant, and in sepsis and oncology settings. Findings across trials are mixed; some report changes in selected immune markers, while others find no clear clinical benefit. Many studies are small and define outcomes differently, which limits comparison. Regulatory approval is confined to a few countries, and the compound is not an approved drug in the United States or most of Europe.
Overall evidence quality varies considerably. A large share of published reports come from single centers, rely on surrogate immunological markers, or lack adequate control groups. Systematic reviews have highlighted this heterogeneity as a barrier to pooling results. Open questions include which patients, if any, might benefit, what treatment duration is appropriate, and whether any effect is independent of standard care. The peptide is often described as an immune modulator rather than a therapy for one disease, which complicates confirmatory trial design.
| Property | Value | Notes |
|---|---|---|
| Storage temperature, powder | -20 °C or lower | Protect from light and moisture |
| Storage temperature, reconstituted | 2-8 °C | Use within days |
| Purity testing | Reversed-phase HPLC | Separates truncation products |
| Mass confirmation | Mass spectrometry | Detects deamidation and oxidation |
| Common salt forms | Acetate or trifluoroacetate | Affects solubility and weighing |
Storage recommendations center on low temperature, dryness, and protection from repeated freezing and thawing. The intact powder is commonly held at 20 degrees below zero Celsius or colder, while a working solution is divided into single-use aliquots to limit freeze-thaw cycles. Buffered saline or phosphate-buffered saline at neutral pH is frequently used as a diluent. Light sensitivity is not well documented, yet amber vials or foil wrapping are common practice for long-term storage of peptide stocks.
Identity and purity are assessed with a small set of standard peptide methods. Reversed-phase high-performance liquid chromatography separates the main peak from truncated or oxidized species, and its area percentage is the usual purity measure. Mass spectrometry confirms the observed molecular mass against the expected value, while amino acid analysis or peptide mapping checks composition and sequence. Specifications for research-grade material are often stated as 95 percent or higher, though the exact limit depends on the supplier and the intended use.
The peptide is generated in cells by cleavage of prothymosin alpha, a larger acidic protein encoded by the PTMA gene. Prothymosin alpha is expressed in many tissues, not only in the thymus, and its functions include nuclear roles in chromatin-related processes. The 28-residue fragment corresponds to the N-terminal portion of that precursor. How the cleavage occurs and how the fragment's concentration is regulated remain open questions; circulating amounts are small and difficult to measure reliably with routine assays.
Thymosin alpha 1 is a short peptide first isolated from bovine thymus tissue in the early 1970s during fractionation work aimed at identifying factors that influence T cell development. It belongs to a family of acidic thymic peptides, and the original preparations contained several components that were later separated by chromatography. The compound is now produced synthetically rather than extracted from tissue, which removes batch variability tied to animal sourcing. Researchers describe it as an immunomodulatory peptide because laboratory studies show effects on several cell types of the innate and adaptive immune systems.
The molecule consists of 28 amino acid residues with an acetyl group attached to the N-terminal serine. Its sequence is acidic overall, with several glutamic and aspartic acid residues distributed along the chain and no cysteine, so disulfide bridges do not form. The peptide carries a net negative charge at physiological pH. Because the N-terminus is blocked, the intact molecule resists degradation by many aminopeptidases, which contributes to its stability in biological fluids.
临床研究将Tα1用于慢性病毒感染、肿瘤辅助治疗和疫苗佐剂等场景。部分试验报告了免疫学指标改善，但临床终点获益在不同研究中并不一致。系统综述指出，研究间在人群、剂量和联合方案上差异较大，难以汇总结论。因此，Tα1的确切临床地位仍属开放问题，需要更多高质量随机对照试验来澄清。其机制研究也需从体外实验向体内模型推进。
胸腺素α1对免疫系统的影响涉及多种细胞类型。研究表明，它可促进未成熟T细胞向成熟T细胞分化，并增强T细胞对抗原刺激的增殖反应。树突状细胞在Tα1存在下表达更高水平的共刺激分子，从而更有效地呈递抗原。此外，自然杀伤细胞的活性也观察到上升。这些效应并非直接杀伤病原体，而是调节宿主免疫应答的强度与方向。
Most published studies on thymosin alpha-1 report changes in immune measurements rather than clinical outcomes, and findings differ across designs and populations. Whether the peptide signals through one defined receptor or through several less specific interactions remains an open question. Its reported circulation half-life of a few hours complicates comparison of dosing schedules across trials. Mechanistic claims are frequently drawn from isolated cell cultures, and how far those results extend to whole organisms is unresolved.
Thymosin alpha-1 is a synthetic peptide of 28 amino acids whose sequence matches the amino-terminal region of prothymosin alpha. The chain is acetylated at its first residue and contains one disulfide bridge between two cysteine residues, which folds the molecule into a compact loop. Its molecular formula, C129H215N33O55, corresponds to a monoisotopic mass of roughly 3,106 daltons. Material used in laboratories is made by solid-phase synthesis rather than isolated from animal tissue.
Early work on thymic extracts in the 1960s described a heat-stable acidic fraction containing many polypeptides. Separation of that mixture yielded individual components, and thymosin alpha-1 was named as one of them on the basis of assays for T-cell activity. The first preparations came from calf thymus, while subsequent research and clinical material has been chemically synthesized. Nomenclature in older papers is inconsistent, and the same peptide sometimes appears under different designations, which complicates literature searches.
Die vergrößerte Kettenlänge reduziert die Integrin-Bindung oder verhindert sie komplett. Die RGE-Mäuse zeigten einen ähnlichen Phänotyp wie Mäuse, denen TGFβ1 komplett fehlt. Dies deutet darauf hin, dass eine fehlende Aktivierung von TGFβ1 durch ein Integrin gleichbedeutend ist mit der kompletten Abwesenheit von TGFβ1, mithin also die Aktivierung durch RGD-bindende Integrine – unabhängig von der Frage, welche der 8 möglichen Subtypen genau welche Rolle spielen – essentiell für die biologische Aktivität von TGFβ1 ist. Während sowohl αvβ6- als auch αvβ8-Integrin an die RGD-Sequenz in LAP binden, welches in der latenten Form als Komplex mit TGFβ1 und TGFβ3 vorliegt, ist der jeweilige Aktivierungsmechanismus durch die beiden Integrine verschieden.
==== Aktivierung durch αvβ6-Integrin ==== Die Aktivierung von TGFβ durch αvβ6-Integrin beruht auf eine Änderung der Konformation von LAP durch mechanische Zugkräfte. Damit dies möglich ist, muss das LAP/TGFβ-Heterodimer an einem Ende stabil verankert sein, während am anderen Ende Zellen mittels αvβ6-Integrin an einem LAP-Protein ziehen müssen. Eine stabile Verankerung erfolgt durch eine Verknüpfung an extrazelluläre Matrix (EZM)-Proteine mittels LTBP oder an die Oberfläche einer benachbarten Zelle durch GARP. Die Zugkraft durch die Zelle ist erst infolge einer Bindung von αvβ6-Integrin an die RGD-Sequenz in LAP gegeben, da dieses Integrin mit seiner intrazellulären Komponente mittels fokaler Adhäsionen an kontraktile Aktinfilamente verknüpft ist. Molekulare Simulationen basierend auf einer αvβ6-LAP/TGFβ1-Struktur haben gezeigt, wie mechanische Zugkräfte zu konformationellen Änderungen von LAP führen, die schließlich TGFβ1 aus der LAP-Klammer befreien. Aktives TGFβ1 wird durch diesen Prozess von der Bindung an EZM-Proteine befreit und liegt löslich im interstitiellen Medium vor. Andere Integrine, z. B. αvβ1, αvβ3, αvβ5 und α8β1, sind wie αvβ6 in der Lage, durch Aktinfilamente Zugkräfte in die EZM zu übertragen. Falls diese Integrine eine Rolle für die TGFβ-Aktivierung in Organismen spielen, ist daher anzunehmen, dass sie ebenfalls den hier beschriebenen Mechanismus zur TGFβ-Aktivierung benutzen.
==== Aktivierung durch αvβ8-Integrin ==== β8-Integrin hat eine cytoplasmatische Aminosäuresequenz, die sich stark von der aller anderen β-Integrine unterscheidet. Insbesondere fehlt β8-Integrin die intrazelluläre Domäne, um fokale Adhäsionen ausbilden und sich über Adapterproteine an kontraktile Aktinfilamente zu binden. Eine Aktivierung von TGFβ über Zugkraft kommt daher für αvβ8-Integrin sehr wahrscheinlich nicht in Frage. Es wurde bisher vermutet, dass die Bindung von TGFβ an αvβ8-Integrin eher die Rekrutierung von Proteasen ermöglicht, welche dann die LAP-Klammer öffnen, damit TGFβ freigesetzt werden und zu TGFβ-Rezeptoren diffundieren kann. Mittlerweile hat sich aber gezeigt, dass αvβ8-Integrin eine Aktivierung von TGFβ1 ermöglicht, bei der TGFβ1 nicht komplett freigesetzt wird, aber sein Rezeptor-Bindungsmotiv soweit exponiert wird, dass es auch im LAP-gebundenen Zustand in der Lage ist, an TGFβ-Rezeptoren zu binden.
Sources: de.wikipedia.org
Plasmin Proteasen (u. a. MMP-9, MMP-13) Thrombospondin Scherkräfte Sauerstoffradikale (ROS, reactive oxygen species) pH-Wert Im Vergleich zur Aktivierung durch Integrine sind die Belege für die TGFβ-Aktivierung durch die hier genannten Faktoren weniger konsistent. Dies wird auch durch ein evolutionsbiologisches Argument unterstützt: Integrine waren bereits vorhanden, als TGFβ entstanden. Plasmin, die genannten Proteasen und Thrombospondin entstanden dagegen erst später. Dies bedeutet jedoch nicht, dass integrinunabhängige Aktivierungsmechanismen in bestimmten Situationen nicht über TGFβ-Aktivierung entscheiden könnten.
Sources: de.wikipedia.org
Dry lyophilized powder tolerates short ambient exposure during handling and shipping. Long-term room-temperature storage is not recommended because moisture uptake and slow degradation can occur over months. Storage at minus twenty degrees Celsius is the common practice for extended periods.
Typical entries list appearance, identity by mass spectrometry, purity by chromatography, water or moisture content, and residual counter-ion. Some certificates also report microbial limits and endotoxin for materials intended for laboratory use. The reported methods and acceptance ranges vary between suppliers.
The peptide is often supplied as an acetate or trifluoroacetate salt, and the counter-ion affects solubility, weight-per-mole calculations, and compatibility with cell assays. Trifluoroacetate can be undesirable in some biological experiments. Knowing the salt form is necessary for accurate concentration determination.
Trials differ in patient population, dose schedule, background treatment, and the endpoints used to judge success. Many are small and single-center, so random variation can dominate the reported effects.