LL-37

LL-37 is a naturally occurring antimicrobial peptide that plays a role in the body's innate immune system. It is primarily known for activity against a wide range of pathogens, including bacteria, viruses, and fungi, by disrupting microbial membranes. It also supports the initial immune defense at sites of injury or inflammation. In research models it binds cell membranes, modulates immune cell activity, and is studied for barrier integrity and wound healing.

• Antimicrobial defense
• Immune support
• Tissue healing
• Inflammation modulation
• Barrier integrity support

• Helps disrupt microbial membranes, including bacteria, viruses, and fungi in research models
• Modulates immune cell activation
• Supports controlled inflammation
• Promotes tissue repair and regeneration
• Helps maintain skin and mucous membrane integrity

Reconstitution

1 mL bacteriostatic water

Final concentration

5 mg/mL (5,000 mcg/mL)

Dosage range

250–500 mcg (5–10 units)

Frequency

The sheet lists both 5 days on and 2 days off, and a separate 4 weeks on and 1 week off pattern

Research duration

Up to about 50 days straight, then 4 weeks off, as one pattern on the sheet

Administration

Subcutaneous, as noted on the sheet

Notes

The sheet notes local irritation can occur and says to hold the dose if marked irritation develops.

Research duration on the sheet: The sheet describes cycles of about 4–8 weeks, or up to about 50 days, followed by time off.

• 5 mg + 1 mL bacteriostatic water = 5 mg/mL.
• 5 units = 250 mcg. 10 units = 500 mcg.

• The sheet gives a range of 250–500 mcg rather than a weekly escalation.
• 5 units = 250 mcg and 10 units = 500 mcg at this concentration.

• For educational and research purposes only.
• Not for human use.
• Limited human-research data.
• Use only as part of a broader research protocol.
• Store appropriately after reconstitution.

• The sheet notes possible injection-site irritation.

Human research

Emerging

Animal research

Moderate

Mechanistic evidence

Strong

Long-term safety data

Limited

Completed published studies are listed below and labeled as in vitro, animal, or human research. Favorable and unfavorable results are both included, including cancer studies. This is not every paper on the compound, and it is not a recommendation or a dose.

Cancer results go both ways. Full-length LL-37 increased ovarian cancer cell growth and, in a separate study, slowed colon cancer. A short fragment of LL-37 also killed colon cancer cells in culture.

• Wound healing activity of the human antimicrobial peptide LL-37Animal

  Mice treated with a steroid that slows repair. Topical LL-37 increased new blood vessels and skin closure.

• LL-37 increases ovarian cancer cell proliferation and invasionIn vitro

  Ovarian tumors contained more LL-37 than normal ovary. Adding LL-37 to ovarian cancer cells increased division, movement, and invasion.

• LL-37 promotes ovarian tumor growth by recruiting stromal cellsAnimal

  Mice with ovarian tumor grafts. Blocking LL-37 reduced stromal-cell entry into the tumor and slowed tumor growth.

• LL-37 suppresses colon cancer through a cell-death pathwayIn vitro

  Colon cancer cells died after LL-37 exposure. Mice lacking the related cathelicidin peptide grew more colon tumors after a carcinogen.

• FK-16, a fragment of LL-37, and colon cancer cellsIn vitro

  Colon cancer cells in culture. FK-16, residues 17–32 of LL-37 rather than the full peptide, killed the cells through two death pathways.

5 mg vial. Format: Lyophilized powder.