Thymulin
Also known as: FTS · Serum Thymic Factor · Facteur Thymique Serique · Thymic humoral factor
The only true thymic hormone (not a thymosin). A zinc-dependent nonapeptide naturally produced by thymic epithelial cells that directly matures T-lymphocytes. Levels decline ~90% between ages 20-60, making it a key driver of immunosenescence. Requires zinc coordination to be biologically active. Distinct from Thymalin (polypeptide extract) and Thymosin Alpha-1.
What is Thymulin? The only true thymic hormone (not a thymosin). A zinc-dependent nonapeptide naturally produced by thymic epithelial cells that directly matures T-lymphocytes. Levels decline ~90% between ages 20-60, making it a key driver of immunosenescence. Requires zinc coordination to be biologically active. Distinct from Thymalin (polypeptide extract) and Thymosin Alpha-1.
How does Thymulin work? Thymulin requires zinc coordination to bind specific receptors on T-lymphocyte precursors. In its zinc-bound form it induces expression of T-cell surface antigens (Thy-1, Lyt-1, Lyt-2) and promotes differentiation into functional CD4+ and CD8+ T-cells. Also induces IL-2 receptor expression enhancing T-cell proliferative responses. The dramatic age-related decline in thymulin correlates directly with immunosenescence and cancer susceptibility.
Benefits of Thymulin: The only true thymic hormone — directly matures T-lymphocytes; Restores age-related T-cell deficiency (immunosenescence); Zinc-dependent biological activity; Anti-tumor immune activation; Autoimmune disease modulation in research; Restores NK cell activity in aging; Clinical data in cancer, HIV, and autoimmunity
Thymulin dosage: Typical dose: 100-400mcg 3x/week. CRITICAL: Ensure zinc sufficiency (supplement 15-25mg zinc/day if needed) as zinc coordination is required for activity. 4-6 week cycles.
Research status: Research Only
Source: PeptideWiki — https://www.peptide-wiki.net/peptides/thymulin
Mechanism of Action
Thymulin requires zinc coordination to bind specific receptors on T-lymphocyte precursors. In its zinc-bound form it induces expression of T-cell surface antigens (Thy-1, Lyt-1, Lyt-2) and promotes differentiation into functional CD4+ and CD8+ T-cells. Also induces IL-2 receptor expression enhancing T-cell proliferative responses. The dramatic age-related decline in thymulin correlates directly with immunosenescence and cancer susceptibility.
Benefits
- The only true thymic hormone — directly matures T-lymphocytes
- Restores age-related T-cell deficiency (immunosenescence)
- Zinc-dependent biological activity
- Anti-tumor immune activation
- Autoimmune disease modulation in research
- Restores NK cell activity in aging
- Clinical data in cancer, HIV, and autoimmunity
Side Effects & Risks
- Zinc deficiency will inactivate the peptide — ensure adequate zinc status
- Generally very well tolerated with long clinical history
- Injection site reactions
Where to Buy Thymulin
1 option across 1 vendor · Sorted cheapest first · All include direct product link
From
$65.00
All links are affiliate links — PeptideWiki earns a commission at no extra cost to you. Coupon codes apply at checkout. Prices and availability may change. Always verify COA before purchasing.
Storage & Reconstitution Guide
Storage Temperature
-20°C (lyophilized)
24 months (lyophilized), 28 days (reconstituted)
Reconstitution Solvent
Bacteriostatic water (BAC water)
Swirl gently — do not shake or vortex
Handling Notes
Protect lyophilized peptide from moisture and light. Once reconstituted, keep refrigerated. Discard if solution becomes cloudy or discolored. Use insulin syringe for precise dosing.
Step-by-Step Reconstitution
Gather supplies
BAC water, insulin syringe, alcohol swabs, vial
Disinfect tops
Swab rubber stoppers of both vials with alcohol
Draw BAC water
Pull desired mL of BAC water into syringe
Inject slowly
Inject BAC water down the side of the peptide vial, swirl gently to dissolve
Preclinical Research & Reviews1
Thymulin serum levels and zinc status across age groups
Study demonstrated ~90% decline in thymulin activity from ages 20-60. Zinc supplementation restored thymulin activity in elderly subjects with borderline zinc deficiency.
Key Finding
~90% decline in thymulin from ages 20-60
Zinc Intervention
Zinc restored thymulin activity in elderly
Clinical Relevance
Thymulin decline is a key driver of immunosenescence
Research Protocol
- Dose Range
- 100–400 mcg
- Frequency
- 3x per week subcutaneous
- Cycle
- 4-6 weeks
- Routes
- subcutaneous injection
- Notes
- Typical dose: 100-400mcg 3x/week. CRITICAL: Ensure zinc sufficiency (supplement 15-25mg zinc/day if needed) as zinc coordination is required for activity. 4-6 week cycles.
Legal & Regulatory Status
Sold for research purposes only. Not for human use. Laws vary by country.
Commonly Stacked With
View all peptide stacks →External Resources
Chemical Properties
- CAS Number
- 63958-90-7
- Mol. Weight
- 858.9 Da
- Formula
- C33H54N12O15S
PeptideWiki Research Team
Evidence-based research data sourced from PubMed and ClinicalTrials.gov · Last updated: February 25, 2026
Frequently Asked Questions About Thymulin
What is Thymulin?▾
The only true thymic hormone (not a thymosin). A zinc-dependent nonapeptide naturally produced by thymic epithelial cells that directly matures T-lymphocytes. Levels decline ~90% between ages 20-60, making it a key driver of immunosenescence. Requires zinc coordination to be biologically active. Distinct from Thymalin (polypeptide extract) and Thymosin Alpha-1.
What are the benefits of Thymulin?▾
The only true thymic hormone — directly matures T-lymphocytes
What are the benefits of Thymulin?▾
Restores age-related T-cell deficiency (immunosenescence)
What are the side effects of Thymulin?▾
Zinc deficiency will inactivate the peptide — ensure adequate zinc status
What is the recommended dosage for Thymulin?▾
Typical dose: 100-400mcg 3x/week. CRITICAL: Ensure zinc sufficiency (supplement 15-25mg zinc/day if needed) as zinc coordination is required for activity. 4-6 week cycles.
How long should a Thymulin cycle last?▾
4-6 weeks
More Immune Support Peptides
View all Immune Support peptides →Thymalin
Thymus polypeptide complex
A polypeptide complex extracted from calf thymus gland that broadly modulates immune function. Distinct from Thymosin Alpha-1 (a single purified peptide), Thymalin is a complex mixture of thymic peptides. Russian clinical trials show 2-2.4x reduction in acute respiratory infections and significant mortality reduction in elderly patients.
LL-37
Cathelicidin
The only human cathelicidin antimicrobial peptide, naturally produced by immune cells as a first-line defense. Has broad-spectrum antimicrobial, wound healing, and immunomodulatory properties.
Thymosin Alpha-1
Tα1
A 28-amino acid peptide naturally produced by the thymus gland that modulates both innate and adaptive immunity. Approved under the name Zadaxin in some countries for hepatitis B, C, and as a vaccine adjuvant.