Side-by-side · Research reference

LL-37vsThymosin α-1

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AHuman-MechanisticHUMAN-REVIEWED15/35 cited

BPhase 3HUMAN-REVIEWED8/39 cited

LL-37

Cathelicidin · Human AMP

Broad-spectrumAntimicrobial activity

Membrane disruptionPrimary mechanismLu 2026 He 2026

Innate immunityHost defense rolePinheiro 2026 Zhang 2026

Endogenous · Secreted at inflammation sites

Thymosin α-1

Immune modulator · Approved (some countries)

1.6 mgPer doseIyer 2007

Phase 3Evidence levelIyer 2007 Camerini 2001

~2 hrHalf-life

SQ · 2× weekly · 6+ months for chronic indications

01Mechanism of Action

Parameter

LL-37

Thymosin α-1

Primary target

Bacterial membranes · Phosphatidylserine-exposed cellsHe 2026 Lu 2026

Toll-like receptor 9 (TLR9) + T-cell maturation pathwayCamerini 2001

Pathway

hCAP-18 precursor → Proteinase-3 cleavage → LL-37 release → Membrane insertion/disruption

TLR9 activation → ↑ IFN-α + IL-2 + IFN-γ → enhanced T-cell function + dendritic cell maturationIyer 2007

Downstream effect

Membrane permeabilization, cytokine induction, autophagy, phagosome-lysosome fusion, chemotaxisAhmad 2026 Zhang 2026

Restored T-cell function, improved viral clearance, anti-tumour adjuvant effectsIyer 2007

Feedback intact?

—

Origin

Endogenous human cathelicidin (37-AA fragment, residues 134–170 of hCAP-18)

Synthetic 28-AA peptide identical to natural Tα-1 isolated from thymus extractCamerini 2001

Antibody development

—

02Dosage Protocols

Parameter

LL-37

Thymosin α-1

Endogenous expression

Constitutive in neutrophils, epithelial tissues

Upregulated during infection and inflammation.Pinheiro 2026

—

Exogenous (experimental)

Dose varies by study; antimalarial ~10–50 μM in vitro

No FDA-approved exogenous formulation.

—

Plasma levels (malaria)

Elevated in infected patients and miceHe 2026

Exogenous administration reduced parasitemia in murine models.He 2026

—

Evidence basis

In vitro, animal models, human observational

Phase 3 + approved (35+ countries as Zadaxin)Iyer 2007

Standard dose (HBV/HCV)

—

1.6 mg SQ 2× weekly × 6–12 monthsIyer 2007

Frequency

—

2× weekly (Mon/Thu typical)

Lower / starter dose

—

0.8 mg per injection

Duration

—

6–12 months for chronic indications

Reconstitution

—

Sterile water for injection per vial label

Timing

—

No specific time

Half-life

—

~2 hours plasma; tissue effect days

04Side Effects & Safety

Parameter

LL-37

Thymosin α-1

Cytotoxicity (high dose)

Membrane disruption in host cells at supraphysiological concentrations

—

Pro-inflammatory signaling

Can exacerbate inflammation in certain contexts (context-dependent)Pinheiro 2026

—

Biofilm formation risk

LL-37-DNA complexes may stabilize dental plaque biofilmsTanabe 2026

—

Theoretical cancer risk

Immunomodulatory roles in tumor microenvironment under investigation

—

Injection site reaction

—

Erythema, mild discomfort

GI symptoms

—

Rare nausea

Fatigue

—

Common during initial weeks

Fever / flu-like

—

Mild interferon-like response possible

Autoimmune

—

Theoretical risk; caution in active autoimmune disease

Cancer risk

—

No signal — used as adjuvant in oncology

Pregnancy / OB

—

Avoid

Absolute Contraindications

LL-37

—

Thymosin α-1

·Pregnancy / breastfeeding
·Hypersensitivity to peptide
·Concurrent immunosuppressant therapy (transplant patients)

Relative Contraindications

LL-37

·Active autoimmune disease (theoretical immune dysregulation)

Thymosin α-1

·Active autoimmune disease
·Severe immunocompromised state without supervision

05Administration Protocol

Parameter

LL-37

Thymosin α-1

1. Natural secretion

LL-37 is constitutively expressed in neutrophils and epithelial cells, cleaved from hCAP-18 by proteinase-3 at sites of infection or inflammation.

Add 1 mL sterile water per 1.6 mg vial → 1.6 mg/mL.

2. Experimental formulations

Synthetic LL-37 and derivatives (e.g., SAMP-12aa) tested in vitro and animal models. Administered via topical, intraperitoneal, or intravenous routes in research settings.

SQ — abdomen, thigh, or upper arm. Rotate sites.

3. Stability considerations

LL-37 is resistant to pepsin degradation at gastric pH. Synthetic short peptides designed to retain this stability while reducing toxicity.Lu 2026

2× weekly, e.g. Monday + Thursday.

4. Storage

—

Lyophilised: refrigerate. Reconstituted: refrigerate, use within 24 h.

5. Needle

—

27–31G, 4–8 mm insulin syringe.