What is LL-37?
LL-37 is the only human member of the cathelicidin family, a group of endogenous antimicrobial peptides. It is part of the innate immune defense, fights bacteria directly and plays a role in inflammation and wound healing.
How it works
LL-37 directly disrupts the membrane of bacteria and so acts antimicrobially. It also modulates the immune response and is involved in tissue repair. This dual role makes it interesting in research but also complex, because too much LL-37 can also fuel inflammation.
What you need
- The LL-37 vial (lyophilized powder).
- Bacteriostatic water, U-100 insulin syringes, alcohol swabs.
Reconstitution
Use the calculator above. A 5mg vial with 2ml water gives 2500mcg per ml, 250mcg is then 10 units on the U-100 syringe. Just add the water to the vial and let it dissolve.
Dosing
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Injection
Subcutaneous into the subcutaneous fat. Disinfect the site, pinch a skin fold, rotate sites.
What the research shows
A widely cited review (Dürr, 2006) summarizes the structure and function of LL-37 as the only human cathelicidin: antimicrobial, immunomodulating, involved in wound healing. That is well-described basic biology, but controlled studies on injected LL-37 as an agent in humans are missing.
Side effects
- Solid human use data are missing.
- Local reactions at the injection site, since LL-37 is membrane-active.
- Theoretically, too much LL-37 can amplify inflammation rather than dampen it.
Storage
Before mixing the powder is robust, normal room temperature (around 20 to 25 degrees) is fine, ideally kept in the dark. After mixing, keep in the fridge (2 to 8 degrees), do not freeze. It stays good there for at least 8 to 10 weeks with barely any loss of potency, in practice considerably longer. Swirl or shake to mix, both are fine.