LL-37

LL-37 is the body's primary cathelicidin antimicrobial peptide, studied for wound healing, antimicrobial defense, and immune modulation, with stronger topical and preclinical evidence than systemic subcutaneous data.

Profile · 01

Overview

LL-37 is a 37-amino-acid cationic antimicrobial peptide derived from hCAP18 and represents the only recognized human cathelicidin. Its amphipathic alpha-helical structure helps explain both direct antimicrobial membrane effects and broader host-defense signaling.

The source includes human wound-healing trial context for topical use as well as preclinical sepsis and immune-modulation literature. This page summarizes the once-daily subcutaneous protocol from the source while noting that systemic dosing remains more extrapolative than the wound-healing literature itself.

At a Glance

Goal
Support antimicrobial defense, wound-healing signaling, and immune modulation in a research context
Categories
AntimicrobialWound HealingImmune ModulationTissue Repair
Synergistic
Thymosin Alpha-1 · BPC-157 · GHK-Cu
Profile · 02

Protocol

Suggested once-daily titration approach with weekly increases from 50 mcg to 400 mcg.

Reconstitute
Add 3.0 mL bacteriostatic water to a 5 mg vial for about 1.67 mg/mL concentration
Typical daily range
100-400 mcg once daily
Start
50 mcg daily for Week 1
Target
200-400 mcg daily by Weeks 4-8
Frequency
Once daily (subcutaneous); some protocols discuss 5 days on, 2 days off
Cycle Length
8-12 weeks with optional extension to 16 weeks
Timing
Any consistent time; rotate injection sites
Route
Subcutaneous
Cycle
8-12 weeks on, 4 weeks off

Inject once daily subcutaneously using a dilution that keeps higher-dose measurements readable. Early-phase doses are very small, so 30- or 50-unit syringes may improve accuracy. The source notes that clinical wound-healing data exist, but systemic subcutaneous protocols are still largely extrapolated.

Dose progression

Week 1
50 mcg (0.05 mg) · 3 units (0.03 mL)
Week 2
100 mcg (0.10 mg) · 6 units (0.06 mL)
Week 3
150 mcg (0.15 mg) · 9 units (0.09 mL)
Week 4
200 mcg (0.20 mg) · 12 units (0.12 mL)
Week 5
250 mcg (0.25 mg) · 15 units (0.15 mL)
Week 6
300 mcg (0.30 mg) · 18 units (0.18 mL)
Week 7
350 mcg (0.35 mg) · 21 units (0.21 mL)
Week 8
400 mcg (0.40 mg) · 24 units (0.24 mL)

Important: This guide is for educational purposes only and is not medical advice. For research use only. Not for human consumption.

Science · 01

How LL-37 works.

LL-37 binds preferentially to negatively charged microbial membranes, helping explain direct antibacterial and broader antimicrobial effects. It also interacts with inflammatory and innate-immune pathways, including lipopolysaccharide-binding and TLR-related signaling discussions.

The strongest human evidence cited in the source comes from topical wound-healing settings such as venous leg ulcers and diabetic foot ulcers. Systemic subcutaneous protocols remain research extrapolations rather than established clinical regimens.

Science · 02

Effects

Observations from clinical or preclinical literature.

Human trial literature supports wound-healing benefits in topical ulcer settings
Preclinical literature supports antimicrobial, endotoxin-modulating, and immune-regulating effects
May support tissue-repair research where host-defense signaling is relevant
Systemic human safety data remain limited compared with topical experience
Mild injection-site irritation may occur
Long-term systemic efficacy and safety remain incompletely characterized
Science · 03

Caution

Not recommended during pregnancy or breastfeeding because safety data is insufficient
Use caution in autoimmune conditions because LL-37 participates in immune signaling
Use caution in individuals on immunosuppressive therapy
Avoid assuming topical wound data translates directly to systemic subcutaneous use

Important: This guide is for educational purposes only and is not medical advice. For research use only. Not for human consumption.

Lifestyle · 01

CoFactors

Vitamin D
Supports endogenous cathelicidin expression and broader host-defense biology.
Zinc
Supports wound healing and immune function.
Vitamin C
Supports collagen synthesis and tissue repair.
Omega-3 fatty acids
Support inflammatory balance alongside immune-modulating pathways.
Lifestyle · 02

Life Factors

Complementary strategies for best outcomes.

Support wound healing with adequate protein, zinc, and vitamin C intake where relevant
Optimize vitamin D status because it intersects with cathelicidin biology
Maintain appropriate wound hygiene and standard care if tissue repair is a research goal
Prioritize sleep and recovery because host-defense signaling is recovery-sensitive
Lifestyle · 03

Metrics

Day-to-day metrics worth tracking through the protocol.

  1. Wound-healing progress - monitor dimensions, closure rate, or granulation trends when applicable
  2. Infection markers - note redness, warmth, discharge, or other trend changes
  3. Pain and tissue recovery - useful for local healing-related goals
  4. Injection-site reactions - note redness, swelling, or discomfort
Lifestyle · 04

Labs

Baseline and periodic bloodwork to monitor systemic health during the protocol.

Vitamin D (25-OH)
Relevant to endogenous LL-37 biology and immune support.
CRP (C-Reactive Protein)
Provides broader inflammatory context.
CBC with differential
Useful for immune-cell and infection-related context.
CMP (Comprehensive Metabolic Panel)
Assesses liver and kidney function during the protocol.
Calculators · 01

Supplies Calculator

Estimates assume the schedule defined for this peptide.

Length
Vial size
Bac. water
Syringe
Vials
0 × 5 mg each…
Syringes
0
Bac. water
0 mL
Swabs
02 per syringe
Calculators · 02

Dose Calculator

Dose Calculator

Vial
Bac. water
Syringe
Dose
Concentration
0mcg/mL
Volume per dose
0mL
…
Practice · 01

Preparation

Careful technique preserves potency. Solution should be clear — do not shake.

  1. Allow vial to reach room temperature for 15–20 minutes before reconstitution.
  2. Draw the chosen bacteriostatic water volume with a sterile syringe.
  3. Inject slowly down vial wall; avoid foaming.
  4. Gently swirl/roll until dissolved (do not shake).
  5. Label with reconstitution date and refrigerate at 2–8 °C (35.6–46.4 °F), protected from light.
  6. Use within 30 days; discard any unused solution after 30 days.
Practice · 02

Technique

General subcutaneous guidance from clinical best-practice resources.

Clean the vial stopper and injection site with alcohol and allow them to dry fully
Pinch a skinfold and insert the needle at 45-90 degrees into subcutaneous tissue
Do not aspirate for subcutaneous injections; inject slowly and steadily
Rotate sites across the abdomen, thighs, and upper arms, especially when following a daily schedule
Discard used syringes immediately in a sharps container

Important: This guide is for educational purposes only and is not medical advice. For research use only. Not for human consumption.

Practice · 03

Storage

Lyophilized
Store at room temp in dry, dark conditions; minimize moisture exposure.
Reconstituted
Refrigerate at 2–8 °C (35.6–46.4 °F); avoid freeze–thaw cycles. Discard reconstituted vials after 30 days.

Notes

Allow vials to reach room temperature before opening to reduce condensation uptake.
Reference · 01

Notes

Use a new sterile insulin syringe for each injection and dispose of it safely
Very small early doses may be easier to measure with 30- or 50-unit syringes
The source evidence base is stronger for topical wound-healing applications than for systemic injections
Document dose, timing, and site rotation carefully for consistency
PepTribe is an educational platform. This information is for research and learning purposes only and is not medical advice.
Reference · 02

References

  1. Wound Repair and Regeneration
    Randomized trial evaluating LL-37 in hard-to-heal venous leg ulcers.
    https://pmc.ncbi.nlm.nih.gov/articles/PMC9298190/
  2. Archives of Dermatological Research
    Randomized controlled trial of LL-37 cream in diabetic foot ulcer healing.
    https://pmc.ncbi.nlm.nih.gov/articles/PMC10514151/
  3. Journal of Immunology
    Review of LL-37 in inflammation and autoimmune disease.
    https://pmc.ncbi.nlm.nih.gov/articles/PMC3836506/
  4. Innate Immunity
    Murine sepsis-model work involving LL-37.
    https://pmc.ncbi.nlm.nih.gov/articles/PMC7556193/
  5. CDC
    Subcutaneous injection route guidance.
    https://www.cdc.gov/vaccines/hcp/admin/downloads/YCTS-VaxAdmin-Subcut-injection.pdf
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