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Thymulin: zinc-dependent thymic hormone — immune rejuvenation.

Nonapeptide thymic hormone. Requires zinc for bioactivity. Promotes T-cell maturation and reduces inflammatory cytokines.

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Immune Peptide Research Use Only

Thymulin
Dosage Protocol

Thymulin (Facteur Thymique Sérique, FTS) is a nonapeptide thymic hormone that requires zinc chelation for biological activity. Produced exclusively by thymic epithelial cells, it promotes the maturation and differentiation of T-cell precursors, induces CD3 expression on immature T-cells, and modulates the Th1/Th2 cytokine balance. Thymulin levels decline steeply with age and thymic involution.

20–40 mcg
Per Dose
5–10 day courses
Cycle
SubQ / IM
Route
Daily or every other day
Frequency
Overview

What is Thymulin?

Thymulin was discovered by Bach and Dardenne in 1972 and identified as a zinc-chelating nonapeptide (Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn) produced exclusively by the thymic reticular epithelium. Its unique feature is absolute dependence on zinc for receptor binding — free peptide (unbound to zinc) is inactive. Serum thymulin activity therefore reflects both thymulin production and zinc status.

Thymulin promotes T-cell maturation and differentiation, induces expression of T-cell differentiation markers (CD3, CD4, CD8), and acts as an anti-inflammatory modulator of cytokine production. Research has focused on its potential in autoimmune disease management, aging-related immune decline (immunosenescence), and chronic inflammatory conditions.

🔑
Zinc-Dependent Activation
Requires zinc chelation for receptor binding and biological activity. This zinc-peptide complex is the active form — free peptide is inactive.
🧬
T-Cell Maturation
Induces expression of T-cell surface markers (CD3, CD4, CD8) on immature thymocytes, promoting the differentiation of functional T lymphocytes.
📉
Anti-Inflammatory
Reduces production of pro-inflammatory cytokines (IL-1, TNF-α) and promotes regulatory T-cell function, moderating systemic inflammation.
⏳
Thymic Restoration
Partially restores immune competence in aged animals with thymic involution — a central goal of thymic peptide research in longevity contexts.
Dosing Protocol

Dosing Schedule

Parameters documented in published preclinical and clinical research.

⚠️ Research use only. The following documents parameters from published preclinical and clinical research. Not medical advice. Not for human consumption. Consult a licensed healthcare professional before any use.
PhaseDoseFrequencyDurationNotes
Standard course20 mcgDaily SubQ5–10 daysKhavinson bioregulator protocol: consecutive daily injections only. Repeat 2–3× per year.
Higher dose40 mcgDaily SubQ5–10 daysUpper dose for acute immune research. Do not extend beyond 10 days continuously.
Stack20 mcg + Thymosin Alpha-1Per schedulePer protocolOften stacked with Tα1 for comprehensive thymic restoration.
Off cycle——1–6 monthsRest 1–6 months between courses. Continuous 4–8 week dosing is not the correct protocol for Thymulin.
Safety Profile

Safety & Side Effects

✓ Generally Well Tolerated
Endogenous thymic hormone — well tolerated in research settings
Decades of research publications supporting mechanism
Zinc co-factor requirement is a natural regulatory mechanism
No significant systemic toxicity in preclinical studies
⚠ Potential Concerns
Limited modern RCT data from Western institutions
Must ensure adequate zinc status for activity
Thymic peptide effects may be attenuated in severely immunocompromised subjects
Long-term safety profile not well characterized
⚠️
Research use onlyThis page is an educational reference. None of this constitutes medical advice. Consult a qualified professional before any use. All compounds are for research purposes only.
Evidence Base

Academic References

  1. [1]
    Bach JF, Dardenne M. (1972). Thymus dependency of rosette-forming cells — evidence for a circulating thymic hormone. Transplant Proc. 4(3):345–50. PubMed ↗
  2. [2]
    Dardenne M, et al. (1985). Thymulin, a zinc-requiring hormone secreted by the thymus gland. Biochemistry. 24(13):3407–12. PubMed ↗
  3. [3]
    Mocchegiani E, et al. (2000). Benefit of oral zinc supplementation as an adjunct to zidovudine (AZT) therapy against opportunistic infections in AIDS. Int J Immunopharmacol. 17(9):719–27. PubMed ↗
  4. [4]
    Savino W, Dardenne M. (2000). Neuroendocrine control of thymus physiology. Endocr Rev. 21(4):412–43. PubMed ↗
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