Immune Support Research Guide

LL-37: Dosage, Benefits & Research Guide

Key Facts

LL-37 is a immune support research peptide (C205H340N50O53, MW 4493.34 g/mol). Cationic antimicrobial peptide for immune and wound healing research. It is supplied as a lyophilized powder for laboratory and in-vitro research use only — not for human consumption.

Classification	Cationic antimicrobial peptide for immune and wound healing research.
Molecular Formula	C205H340N50O53
Molecular Weight	4493.34 g/mol
Research Half-Life	Not established in published literature
Form	Lyophilized powder
Research Category	Immune Support

What is LL-37?

LL-37, also known as cathelicidin, is a 37-amino acid cationic antimicrobial peptide (AMP) derived from the C-terminal cleavage of human cathelicidin precursor protein hCAP18. It is the only cathelicidin-derived AMP found in humans and is expressed by neutrophils, epithelial cells, and macrophages. LL-37 kills pathogens through electrostatic interaction with negatively charged microbial membranes, forming toroidal pores that compromise membrane integrity. Beyond direct antimicrobial activity, it modulates innate immunity by acting as a chemoattractant, promoting angiogenesis, and neutralizing bacterial endotoxin (LPS). Research by Zanetti (2004) in Journal of Leukocyte Biology provided a comprehensive characterization of cathelicidin biology and LL-37's multifunctional role in innate defense. Studies in The Journal of Immunology demonstrated that LL-37 exhibited broad-spectrum activity against gram-positive bacteria, gram-negative bacteria, fungi, and enveloped viruses, with minimum inhibitory concentrations in the low micromolar range. Heilborn et al. published findings in Journal of Investigative Dermatology showing that LL-37 expression was significantly reduced in chronic wound beds, and exogenous application promoted re-epithelialization in wound models. Compared to other antimicrobial peptides like defensins (HBD-1, HBD-2), LL-37 has a broader spectrum of activity and more pronounced immunomodulatory effects. Unlike conventional antibiotics, LL-37's membrane-disrupting mechanism makes resistance development unlikely, an increasingly important consideration in antimicrobial research. Store lyophilized LL-37 at -20°C, protected from moisture. Reconstitute with sterile bacteriostatic water and keep at 2-8°C, using within 3 weeks due to potential aggregation. LL-37 is studied by infectious disease researchers, wound healing scientists, immunologists, and antimicrobial resistance specialists investigating peptide-based alternatives to conventional antibiotics.

LL-37 Research Applications

In published and preclinical research, LL-37 has been studied across the following areas:

Antimicrobial activity against bacteria, fungi, viruses
Inflammatory response modulation
Wound healing and tissue repair
Cancer immunotherapy adjuvant research

LL-37 in Research: Reconstitution & Study Concentrations

LL-37 is supplied as a lyophilized powder. For laboratory research it is reconstituted with bacteriostatic or sterile water; the solvent volume sets the working concentration. Published studies select concentrations specific to the assay or model system — there is no human dose, as LL-37 is not approved for human use. Researchers should reference the primary literature for the model in question and document the exact lot COA.

Worked example: a 5mg vial reconstituted with 2 mL of bacteriostatic water yields 2.50 mg/mL.

Open the reconstitution calculator

LL-37 — Frequently Asked Questions

What is LL-37 (Cathelicidin) and how does it work?

LL-37 is a 37-amino acid cationic antimicrobial peptide (AMP) derived from the human cathelicidin precursor protein hCAP-18. It adopts an amphipathic alpha-helical structure that allows it to insert into and disrupt microbial cell membranes. Beyond direct antimicrobial activity, LL-37 modulates the innate immune response by promoting chemotaxis of immune cells, enhancing phagocytosis, and influencing toll-like receptor signaling and cytokine production.

What research has been done on LL-37?

Research published in the Journal of Immunology demonstrated LL-37's broad-spectrum antimicrobial activity against gram-positive and gram-negative bacteria, fungi, and enveloped viruses. Studies in Nature Medicine showed its role in wound healing through promotion of angiogenesis and re-epithelialization. Additional research has explored LL-37 as a potential cancer immunotherapy adjuvant, with studies showing enhanced anti-tumor immune responses when used in combination with conventional treatments.

How does LL-37 compare to other antimicrobial peptides like Thymosin Alpha-1?

LL-37 has direct antimicrobial activity through membrane disruption — it physically kills microorganisms. Thymosin Alpha-1 enhances immune function indirectly by promoting T-cell maturation and dendritic cell activation. For research on direct pathogen elimination, LL-37 is the appropriate tool. For studying adaptive immune enhancement, Thymosin Alpha-1 is more relevant. Some researchers study both to examine innate-adaptive immune cooperation.

What is the recommended reconstitution protocol for LL-37?

For this 5mg vial, add 2 mL of bacteriostatic water to yield a concentration of 2.5mg/mL. Draw 5 units on a 1mL insulin syringe for a 125 mcg dose. Inject BAC water slowly along the inner vial wall — do not shake. Allow the powder to dissolve fully (2–5 minutes). Administer in the AM, every day for 50 days straight. Take 4 weeks off before the next cycle. Refrigerate reconstituted solution at 2–8°C and use within 30 days.

Is LL-37 legal to buy for research?

LL-37 is sold in the United States as a research chemical for laboratory and in-vitro use only. It is not approved by the FDA for human use and is not sold for human consumption. Researchers are responsible for compliance with all applicable federal, state, and institutional regulations.

How is LL-37 reconstituted for research use?

LL-37 ships as a lyophilized (freeze-dried) powder and is reconstituted with bacteriostatic or sterile water before use in research. The volume of solvent added determines the working concentration — use the Elyte reconstitution calculator to derive the exact concentration for a given vial size and solvent volume.

Does LL-37 come with a Certificate of Analysis?

Yes. Every batch of LL-37 from Elyte Peptides ships with a third-party Certificate of Analysis (COA) documenting identity and HPLC purity (≥98%), so research results can be traced to a verified lot.

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