Thymulin
Also known as: Facteur Thymique Sérique, FTS, Serum Thymic Factor, Zinc-Thymulin, Zn-FTS
FTS | Zinc-Dependent Thymic Nonapeptide
Overview
Thymulin is a nonapeptide hormone exclusively secreted by thymic epithelial cells, discovered by Jean-François Bach in the 1970s. Unlike thymalin (a peptide extract mixture), thymulin is a single, defined 9-amino-acid peptide that requires zinc binding for biological activity. It plays a crucial role in T-cell differentiation and maturation within the thymus. Serum thymulin levels decline significantly with age and zinc deficiency, contributing to age-related immune decline (immunosenescence). Research has explored thymulin's potential in restoring immune function, managing autoimmune conditions, and as an anti-inflammatory agent.
Key benefits
- Essential for T-cell maturation and differentiation
- Modulates immune responses (immunomodulatory)
- Anti-inflammatory properties
- Declines with age - restoration may combat immunosenescence
- Well-defined single peptide (unlike extracts)
- Studied in autoimmune disease research
- Neuroendocrine regulatory effects
- Zinc-dependent activity allows for regulation
Mechanism of action
Thymulin exerts its effects through binding to high-affinity receptors on T-lymphocytes and other immune cells. The zinc-thymulin complex is the biologically active form - without zinc, the peptide has no immunological activity. Thymulin promotes: (1) differentiation of immature T-cells into mature T-cell subsets, (2) modulation of cytokine release including IL-2 and interferon-gamma, (3) regulation of T-helper and T-suppressor cell balance, (4) enhancement of NK cell activity, and (5) anti-inflammatory effects through suppression of pro-inflammatory mediators. It also has neuroendocrine effects, influencing the hypothalamic-pituitary-adrenal axis.
Molecular data
- Type
- Thymic nonapeptide hormone
- Half-life
- ~10 minutes (free form); extended with nanoparticle formulations
Sequence
pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn (pyro-Glu N-terminus)
Indications
What the research community uses this compound for, with self-reported effectiveness.
Immune System Research
Immunosenescence
EffectiveAge-related decline in thymulin correlates with reduced immune function; supplementation may restore T-cell parameters.
T-Cell Deficiency
EffectivePromotes differentiation and maturation of T-lymphocytes in thymus.
Zinc Deficiency States
EffectiveThymulin activity depends on zinc; studied in zinc-depleted conditions.
Inflammatory & Autoimmune Research
Anti-Inflammatory Effects
ModerateResearch shows thymulin suppresses pro-inflammatory cytokines and mediators.
Autoimmune Conditions
EmergingInvestigated for potential to restore immune balance in autoimmune states.
Type 1 Diabetes Research
EmergingStudied for effects on pancreatic beta cells and immune modulation in diabetes models.
Neuroendocrine Research
HPA Axis Modulation
ModerateThymulin influences hypothalamic-pituitary-adrenal axis function.
Neuroprotection
EmergingSome research suggests protective effects on neural tissue.
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Injectable
Thymulin is typically administered via subcutaneous or intraperitoneal injection in research settings. As a small peptide, it can also be explored via intranasal delivery for CNS effects. Zinc status should be adequate for biological activity.
| Protocol | Dose | Frequency | Route / duration |
|---|---|---|---|
| Research protocol (immune) Ensure adequate zinc status | 1-10 mcg | Daily | SubQ |
| Intranasal (experimental) For CNS/neuroendocrine effects | Variable | As studied | Intranasal |
Preparation
You will need
- Bacteriostatic water
- Insulin syringes
- Alcohol swabs
- Sterile vial
Steps
- Ensure adequate zinc supplementation for activity
- Reconstitute with bacteriostatic water
- Inject water slowly down vial wall
- Gently swirl until dissolved
- Store refrigerated at 2-8°C
- Use within 4 weeks of reconstitution
Work out the water volume and syringe units in the reconstitution calculator →
Interactions
Pairwise interactions with other compounds you might be cycling — the same data behind the cycle builder's safety check.
Zinc supplementation
SynergisticEssential - thymulin requires zinc for biological activity. Ensure adequate zinc status.
Thymosin Alpha-1
CompatibleDifferent thymic peptides with complementary mechanisms.
Thymalin
CompatibleThymalin is a peptide mixture while thymulin is a single defined peptide; can complement each other.
Epitalon
CompatibleDifferent mechanisms; no known negative interactions.
BPC-157
CompatibleDifferent mechanisms; no known interactions.
Timeline
Typical week-by-week effects reported in clinical and observational data.
- Hours
Receptor binding and initial cellular signaling
- Days 1-7
Immune cell modulation begins; cytokine profile changes
- Weeks 2-4
T-cell differentiation effects; measurable immune parameters
- Months
Long-term immune restoration in research models
Safety
Reported adverse effects, contraindications, and what to monitor on cycle.
Common side effects
- Generally well-tolerated in research
- Injection site reactions (mild)
Rare side effects
- Allergic reactions
- Immune modulation effects
Stop signs — stop and seek advice
- Signs of allergic reaction
- Unexpected immune changes
Contraindications
- Autoimmune diseases (use with medical supervision)
- Organ transplant recipients on immunosuppression
- Pregnancy or breastfeeding
- Known hypersensitivity to thymic peptides
Monitoring
- Zinc status should be adequate
- Immune function panels if available
- T-cell subsets if monitoring research outcomes
Quality checks
What a legitimate product looks like, what should give pause, and what should make you stop.
Good signs
- White lyophilized powder
- Clear solution after reconstitution
- Intact vacuum seal
- Certificate of analysis with sequence verification
Warning signs
- Slight clumping that dissolves easily
Stop signs — don't use
- Discolored powder
- Cloudy solution after reconstitution
- Particulates present
- Broken seal
References
Primary literature and clinical-trial data informing this entry.
Thymulin (FTS) - A Thymic Hormone
Bach JF, Dardenne M · Clinics in Immunology and Immunopathology · 1989
Comprehensive review of thymulin discovery, structure, and immunological functions.
The neuroendocrine role of thymulin
Journal of Neuroimmunology · 2000
Thymulin modulates hypothalamic-pituitary-adrenal axis and has neuroendocrine effects beyond immunity.
Zinc and thymulin
Advances in Experimental Medicine and Biology
Zinc is essential for thymulin biological activity; zinc deficiency causes functional thymulin deficiency.
Thymulin and aging
Mechanisms of Ageing and Development
Serum thymulin levels decline dramatically with age, correlating with immunosenescence and increased infection susceptibility.
Last updated . How this page was sourced is described in the methodology.