If you have been reading about 细胞因子 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.
Last reviewed on 2026-04-17. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
The peptide occurs naturally in thymic tissue and has been detected in serum and other biological fluids. Reported concentrations are low, and reliable measurement generally requires immunoassay or mass spectrometry with an enrichment step. It is released from a larger precursor, prothymosin alpha, by proteolytic cleavage, although the enzymes involved are not fully characterized. Whether circulating levels reflect thymic output specifically remains an open question.
Thymosin alpha 1 is a 28-amino-acid peptide first isolated from thymosin fraction 5, a bovine thymic extract. Its sequence begins with an acetylated serine residue and carries a high proportion of acidic residues, so the molecule has a net negative charge near neutral pH. Despite the shared name, it is unrelated in sequence to the thymosin beta family. Synthetic material prepared by solid-phase peptide synthesis is identical in sequence to the natural peptide.
| Property | Value | Notes |
|---|---|---|
| Class | Synthetic peptide | 28 residues; not a small-molecule compound |
| Molecular mass | About 3,106 Da | Monoisotopic mass of the unmodified chain |
| N-terminal group | Acetylated serine | Present in both native and synthetic forms |
| Secondary structure | Disulfide-constrained loop | One bridge between two cysteine residues |
| Typical source | Solid-phase synthesis | Early isolates came from bovine thymus extracts |
Biologically, the peptide is studied mainly in the context of immune cell development and regulation. It is produced in the thymus and in several other tissues, and it appears to influence the maturation and activity of T cells and other immune populations. Laboratory work describes effects on cytokine production, on the balance between T cell subsets, and on the function of dendritic cells. Much of this evidence comes from cell culture and animal models, so the extent to which the same pathways operate in humans remains an open question.
Clinical interest has centered on chronic viral hepatitis, on immune restoration in various conditions, and on use as an adjuvant intended to improve responses to vaccines. Trials have reported mixed results, and regulatory status differs sharply between countries; in some places it is a prescription product, while elsewhere it is sold without an approved therapeutic indication. Because published studies vary widely in design, population, and endpoints, comparisons across them are difficult and no single conclusion covers the whole literature.
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.
Lyophilized material is typically treated as a hygroscopic solid that should be brought to room temperature before the container is opened, which limits condensation on the powder. Reconstitution is commonly done with sterile water or a buffered diluent, and gentle mixing is preferred over vigorous agitation to reduce foaming and surface adsorption. Because peptides can bind to plastic and glass, diluents containing a small amount of carrier protein are sometimes used in laboratory work. Working solutions are generally aliquoted and prepared fresh rather than subjected to repeated freezing and thawing.
Stability depends on temperature, pH, and the number of freeze-thaw events the sample has experienced. Freeze-dried material is commonly held at -20 °C or colder, while reconstituted liquid is kept cold and used within a short window. Extreme pH and prolonged light exposure can promote deamidation, oxidation, or aggregation, particularly at asparagine and methionine positions. Adsorption to container walls can lower the measured concentration of a dilute solution even when the peptide molecules themselves remain intact.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or chemically modified byproducts. Mass spectrometry confirms the expected molecular mass and can indicate acetylation state or sequence errors. Amino acid analysis and peptide mapping supply complementary sequence-level information, while endotoxin testing is relevant for preparations intended for cell or animal work. Purity figures reported by suppliers refer to the method used and are not directly comparable across laboratories unless conditions are stated.
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。
在信号层面，Tα1可能通过Toll样受体等模式识别受体发挥作用。部分实验显示，它能激活髓样分化因子88依赖的通路，进而促进核因子κB进入细胞核。这导致白细胞介素2、干扰素γ和白细胞介素12等细胞因子的转录增加。这些细胞因子偏向辅助性T细胞1型应答，有助于细胞免疫。然而，具体受体和结合位点尚未完全确定，不同实验模型的结果存在差异。
The objectives of the Party of European Socialists, the European Parliament's social democratic bloc, are now "to pursue international aims in respect of the principles on which the European Union is based, namely principles of freedom, equality, solidarity, democracy, respect of Human Rights and Fundamental Freedoms, and respect for the Rule of Law." As a result, today the rallying cry of the French Revolution—Liberté, égalité, fraternité—is promoted as essential socialist values. To the left of the European Socialists at the European level is the Party of the European Left, a political party at the European level and an association of democratic socialist and communist parties in the European Union and other European countries. It was formed for the purposes of running in the 2004 European Parliament election. The European Left was founded on 8–9 May 2004 in Rome. Elected MEPs from member parties of the European Left sit in the European United Left–Nordic Green Left group in the European Parliament. The democratic socialist Left Party in Germany grew in popularity, as did popular dissatisfaction with the increasingly neoliberal policies of the Social Democratic Party of Germany after Gerhard Schröder's tenure as Chancellor, becoming the fourth biggest party in parliament in the general election on 27 September 2009. In 2008, the Progressive Party of Working People candidate Dimitris Christofias won a crucial presidential runoff in Cyprus, defeating his conservative rival with a majority of 53%.
== Further reading == Davies, Catherine, and Richard John Miron. PRF in Facial Esthetics. Batavia, IL: International Quintessence Publishing Group. 2020. Sachdev, Mukta, and Niti Khunger. Essentials for Aesthetic Dermatology in Ethnic Skin. CRC Press, 29 May 2023. Zoe Kececioglu Draelos. Cosmetic Dermatology: Products and Procedures. Chichester, West Sussex; Hoboken, Nj, John Wiley & Sons, Inc, 2016. Wilfried Rähse, and Wiley-Vch. Cosmetic Creams: Development, Manufacture and Marketing of Effective Skin Care Products. Weinheim Wiley-Vch, 2020.
=== Pharmacokinetics === The disposition of oveporexton is biexponential and it has an elimination half-life of 16 to 24 hours in humans. The FDA label gives a more specific mean terminal elimination half-life of 23.2 hours.
=== Medications === Certain medications can cause either weight loss or weight gain. Side effects are often listed for each medication and should be considered when attempting to manage a person's weight. Semaglutide is an anti-obesity drug that is also used for blood sugar control.
== R == Radial glial cell A type of glial cell present during brain development that serves as a scaffold for migrating neurons and acts as a neural progenitor cell. Rasmussen's encephalitis A rare chronic inflammatory neurological disorder that typically affects one hemisphere of the brain, causing seizures, progressive weakness, and cognitive decline. Receptor potential A change in membrane potential in a sensory receptor cell in response to a stimulus. It may trigger action potentials in sensory neurons. Receptor tyrosine kinase (RTK) A class of receptors involved in cell growth and differentiation. In neuroscience, RTKs mediate responses to neurotrophic factors like BDNF and NGF. Reelin A protein involved in regulating neuronal migration and positioning during brain development. Disruption is associated with lissencephaly and schizophrenia. Reflex A rapid, automatic motor response to a stimulus, often mediated by the spinal cord without conscious brain involvement. Refractory period A brief period following an action potential during which a neuron is less excitable or unable to fire another action potential. Relative refractory period The phase during which a neuron can fire another action potential, but only with a stronger-than-normal stimulus. Follows the absolute refractory period. REM sleep (Rapid Eye Movement sleep) A sleep phase characterized by rapid eye movements, vivid dreams, muscle atonia, and heightened brain activity resembling wakefulness.
Sources: en.wikipedia.org
13 December The UK economy shrinks for the second month in a row, with a 0.1% drop in GDP reported for October. The City of London grants planning approval for 1 Undershaft, a new skyscraper that will be tied with the Shard as western Europe's tallest building. 14 December Roisin Quinn, operations director of National Grid plc, confirms that power has been restored to all its customers who experienced outages during Storm Darragh. A number of Irish-themed pubs in the UK have told the BBC they have run out of Guinness after the brewery's owners, Diageo, imposed a limit on supplies in the run up to Christmas. A woman is killed and two men are injured in a shooting in Harlesden, West London. 15 December – UK Foreign Secretary David Lammy says that the British government has made "diplomatic contact" with the Syrian rebel group that overthrew the Assad regime. A £50m humanitarian aid package is announced for vulnerable Syrians. 16 December BBC News reports that Prince Andrew will not join the Royal family at Sandringham for Christmas following revelations about his links to an alleged Chinese spy. Yang Tengbo is named as the alleged Chinese spy with links to Prince Andrew. Archbishop of York Stephen Cottrell, who is to take temporary charge of the Church of England following the resignation of Justin Welby as Archbishop of Canterbury, faces calls for his resignation over his handling of a sexual abuse case while he was Bishop of Chelmsford.
The organ level of organisation in animals can be first detected in flatworms and the more derived phyla, i.e. the bilaterians. The less-advanced taxa (i.e. Placozoa, Porifera, Ctenophora and Cnidaria) do not show unification of their tissues into organs. More complex animals are composed of different organs, which have evolved over time. For example, the liver and heart evolved in the chordates about 550–500 million years ago, while the gut and brain are even more ancient, arising in the ancestor of vertebrates, insects, molluscs, and worms about 700–650 million years ago. Given the ancient origin of most vertebrate organs, researchers have looked for model systems, where organs have evolved more recently, and ideally have evolved multiple times independently. An outstanding model for this kind of research is the placenta, which has evolved more than 100 times independently in vertebrates, has evolved relatively recently in some lineages, and exists in intermediate forms in extant taxa. Studies on the evolution of the placenta have identified a variety of genetic and physiological processes that contribute to the origin and evolution of organs, these include the re-purposing of existing animal tissues, the acquisition of new functional properties by these tissues, and novel interactions of distinct tissue types.
In addition, microfluidics-based devices, capable of continuous sampling and real-time testing of air/water samples for biochemical toxins and other dangerous pathogens, can serve as an always-on "bio-smoke alarm" for early warning. Microfluidic technology has provide tools for biologists to control the cellular environment. Potential advantages of this technology for microbiology are listed below:
In 2013, Xi announced the Belt and Road Initiative (BRI), a global infrastructure and economic development project. Encompassing much of Africa and Eurasia, the BRI became central to Chinese foreign policy and is the largest infrastructure investment by a great power since the Marshall Plan. In 2015, Xi announced the founding of the Asia Infrastructure Investment Bank, seen as a competitor to other multilateral banks such as the World Bank and the Asia Development Bank. Xi has unveiled the Global Development Initiative (GDI), the Global Security Initiative (GSI), the Global Civilisation Initiative (GCI), and the Global Governance Initiative (GGI) in 2021, 2022, 2023 and 2025 respectively, aiming to increase China's influence in the international order. Under Xi, China has, along with Russia, also focused on increasing relations with the Global South in order to blunt the effect of international sanctions.
Sources: en.wikipedia.org
Similarly to the SIR model, also, in this case, we have a Disease-Free-Equilibrium (N,0,0,0) and an Endemic Equilibrium EE, and one can show that, independently from biologically meaningful initial conditions
30 October – Dairy company Fonterra's farmer shareholders vote to authorise the sale of several brands including Mainland and Anchor to French company Lactalis. New Zealand First leader and cabinet minister Winston Peters denounces the sale as "short-sighted." Health New Zealand has confirmed two new cases of measles, bringing the total number of active cases to 13. The number of close contacts has risen to 2,142. 31 October: The Waitangi Tribunal rules that the Citizenship Act 1977 breaches the Treaty of Waitangi by limiting eligibility for citizenship by descent for Māori people to one generation and failing to recognise Māori as tangata whenua ("People of the Land"). A power outage affects 23,000 homes and businesses in the Far North District. Auckland Grammar School instructs Years 9 and 10 students to remain at home after a student tested positive for measles.
== Further reading == E. M. Thurman, M. S. Mills, Solid-Phase Extraction: Principles and Practice, Wiley-Interscience, 1998, ISBN 978-0-471-61422-7 Nigel J.K. Simpson, Solid-Phase Extraction: Principles, Techniques, and Applications, CRC, 2000, ISBN 978-0-8247-0021-8 James S. Fritz, Analytical Solid-Phase Extraction, Wiley-VCH, 1999, ISBN 978-0-471-24667-1
Sources: en.wikipedia.org
Its sequence corresponds to the amino-terminal portion of prothymosin alpha, a larger protein present in many cell types. The isolated 28-residue peptide is a fragment of that protein rather than a separately encoded molecule, and laboratory material is produced by synthesis.
The single bridge between two cysteine residues holds the chain in a folded loop that influences its shape and its behavior in solution. Loss of the bridge through reduction or oxidation shifts chromatographic retention and is tracked during stability work.
It is a defined 28-residue sequence derived from a larger precursor, whereas many other thymic preparations are mixtures of several polypeptides. Its acetylated amino terminus and single disulfide bridge distinguish it chemically from unrelated thymic extracts.
It is a 28-amino-acid peptide originally purified from a bovine thymic extract and later produced synthetically. It is studied mainly for its effects on immune cell function.