In patients with severe sepsis, the body’s immune system releases several antimicrobial proteins, but the peptide LL‑37 does not increase. Higher levels of other proteins are linked to worse heart‑related organ failure and higher death risk, showing they reflect a strong neutrophil response rather than a protective effect you can tap into.

We wanted to investigate if plasma levels of antimicrobial polypeptides (AMPs) are increased in severe sepsis and if they correlate with severity and mortality. Samples were collected from 31 sepsis patients at the intensive care unit. The Sequential Organ Failure Assessment (SOFA) score and 90-day mortality were registered, and inflammatory markers and AMP levels were measured by ELISA. A median SOFA score (13) and cardiovascular SOFA score (3) indicated multiorgan failure with severe circulatory derangement, and elevated cytokine levels indicated inflammatory activation. Levels of bactericidal/permeability-increasing protein, heparin-binding protein, alpha-defensins and lactoferrin but not LL-37 were elevated in sepsis patients compared with controls. Bactericidal/permeability-increasing protein levels correlated with mortality, with lower levels in survivors. Levels of all AMPs, except LL-37, positively correlated with the cardiovascular SOFA score. In conclusion, levels of several AMPs are increased in sepsis and correlate with circulatory derangement. This probably reflects neutrophil activation as part of an innate immune response.