LL-37
A naturally occurring antimicrobial peptide that plays a key role in innate immune defense.
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This information is for educational purposes. Peptide therapy should be guided by a licensed healthcare provider. Connect with a Noho clinician
What is LL-37?
LL-37 is a 37-amino-acid peptide that is the only cathelicidin-derived antimicrobial peptide found in humans. It is produced by immune cells, epithelial cells, and other tissues as part of the innate immune response. It has broad-spectrum antimicrobial activity against bacteria, viruses, and fungi, and also modulates inflammation and wound healing.
Why People Talk About It
Immune system support
EmergingAntimicrobial defense
ModerateGut barrier support
PreliminaryWound healing
PreliminaryHow It Works
LL-37 is part of your body's natural defense system. It can directly kill bacteria and viruses by disrupting their membranes, and it also signals immune cells to respond to threats. Think of it as both a weapon and a signal flare for your immune system.
Common Questions
Safety Information
Common Side Effects
Cautions
- • Limited data on exogenous administration
- • Potential for excessive immune activation
- • Not FDA-approved for therapeutic use
What We Don't Know
The effects of exogenous LL-37 administration are not well characterized in humans. Optimal dosing and safety parameters are not established.
Published Research
35 studiesAssociations between vitamin D status and biomarkers linked with inflammation in patients with asthma: a systematic review and meta-analysis of interventional and observational studies
Impact of vitamin D status and cathelicidin antimicrobial peptide on adults with active pulmonary TB globally: A systematic review and meta-analysis
The Multifunctional Roles of Short Palate, Lung, and Nasal Epithelium Clone 1 in Regulating Airway Surface Liquid and Participating in Airway Host Defense
Transcriptional Profiling of Mycobacterium tuberculosis Exposed to In Vitro Lysosomal Stress
Acute effects of continuous and interval cycling on salivary SIgA and anti-microbial peptide secretions: a randomized crossover trial
Limosilactobacillus fermentum LF61: A multidimensional study on safety and functionality from genomics to clinical application
The Immunomodulatory Activity of High Doses of Vitamin D in Critical Care Patients with Severe SARS-CoV-2 Pneumonia-A Randomized Controlled Trial
Impact of 3-dimensional myofascial release on tumor necrosis factor (TNF) alpha biomarker in nonspecific low back pain: a randomised controlled trial
Effect of weekly vitamin D supplementation on the severity of atopic dermatitis and type 2 immunity biomarkers in children: A randomized controlled trial
Outcomes of High-Dose Versus Low-Dose Vitamin D on Prognosis of Sepsis Requiring Mechanical Ventilation: A Randomized Controlled Trial
Weekly Vitamin D Supplementation to Prevent Acute Respiratory Infections in Young Children at Different Latitudes: A Randomized Controlled Trial
Acute salivary antimicrobial peptide secretion response to different exercise intensities and durations
Efficacy and safety of Oral LL-37 against the Omicron BA.5.1.3 variant of SARS-COV-2: A randomized trial
Efficacy of LL-37 cream in enhancing healing of diabetic foot ulcer: a randomized double-blind controlled trial
Reduction of Erythema in Moderate-Severe Rosacea by a Low Molecular Weight Heparan Sulfate Analog (HSA)
Evaluation of LL-37 in healing of hard-to-heal venous leg ulcers: A multicentric prospective randomized placebo-controlled clinical trial
A randomized controlled trial on the coloprotective effect of coenzyme Q10 on immune-inflammatory cytokines, oxidative status, antimicrobial peptides, and microRNA-146a expression in patients with mild-to-moderate ulcerative colitis
Dose effect of bovine lactoferrin fortification on diarrhea and respiratory tract infections in weaned infants with anemia: A randomized, controlled trial
Functional Antibodies and Innate Immune Responses to WRSS1, a Live Oral Shigella sonnei Vaccine Candidate, in Bangladeshi Adults and Children
The therapeutic efficacy of Bifidobacterium animalis subsp. lactis BB-12(®) in infant colic: A randomised, double blind, placebo-controlled trial
Seasonal Antimicrobial Activity of the Airway: Post-Hoc Analysis of a Randomized Placebo-Controlled Double-Blind Trial
Vitamin D and Phenylbutyrate Supplementation Does Not Modulate Gut Derived Immune Activation in HIV-1
Reduction of respiratory infections in asthma patients supplemented with vitamin D is related to increased serum IL-10 and IFNγ levels and cathelicidin expression
Serum level of cathelicidin LL-37 in patients with active tuberculosis and other infectious diseases
Cow's milk and rice fermented with Lactobacillus paracasei CBA L74 prevent infectious diseases in children: A randomized controlled trial
Impact of high-dose vitamin D(3) on plasma free 25-hydroxyvitamin D concentrations and antimicrobial peptides in critically ill mechanically ventilated adults
Effect of Cholecalciferol Supplementation on Vitamin D Status and Cathelicidin Levels in Sepsis: A Randomized, Placebo-Controlled Trial
Significant Effects of Oral Phenylbutyrate and Vitamin D3 Adjunctive Therapy in Pulmonary Tuberculosis: A Randomized Controlled Trial
Nasal Levels of Antimicrobial Peptides in Allergic Asthma Patients and Healthy Controls: Differences and Effect of a Short 1,25(OH)2 Vitamin D3 Treatment
Treatment with LL-37 is safe and effective in enhancing healing of hard-to-heal venous leg ulcers: a randomized, placebo-controlled clinical trial
Cathelicidin LL-37: a multitask antimicrobial peptide
LL-37, the only human member of the cathelicidin family of antimicrobial peptides
The roles of cathelicidin LL-37 in immune defences and novel clinical applications
A comprehensive summary of LL-37, the factotum human cathelicidin peptide
Therapeutic Potential of Cathelicidin Peptide LL-37, an Antimicrobial Agent, in a Murine Sepsis Model
Always consult a qualified clinician
This information is for educational purposes. Peptide therapy should be guided by a licensed healthcare provider. Connect with a Noho clinician
Research Insights
Related Peptides
Quick Facts
- Class
- Antimicrobial Peptide
- Evidence
- Emerging
- Safety
- Limited Data
- Updated
- Jan 2026
- Citations
- 35PubMed
Also known as
Tags
Related Goals
Evidence Score
Clinical Trials
View Clinical TrialsLinks to ClinicalTrials.gov for reference. Listing does not imply endorsement.
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