Acute inflammation is persistent locally in burn wounds: a pivotal role for complement and C-reactive protein.

Severe burns can cause major complications, such as infection and deforming scar formation. Burn wounds induce an excessive inflammatory response. Serum levels of complement and the acute phase reactant C-reactive protein (CRP) are upregulated in response to burn injury and have been shown to be related to the severity of burn trauma and to the clinical outcome. However, complement and CRP have not been investigated on a tissue level locally at the site of the burn trauma. Protein levels and localization of complement activation product C3d and CRP were determined semi-quantitatively in burn eschar between 2 and 46 days after injury, using immunohistochemistry. CD68 and myeloperoxidase (MPO), markers for macrophages and neutrophilic granulocytes, respectively, were also analyzed on these biopsies. Skin biopsies of very recent surgical wounds (seconds old) served as controls. C3d and CRP are present at high levels in the burn wound. Protein levels of both mediators are significantly elevated up to at least 46 days after injury in comparison with control wounds. In line with this, neutrophils and macrophages infiltrate the burn wound in high numbers up to at least 46 days after injury. The excessive presence of the inflammatory mediators, complement and CRP, and the increased infiltration of neutrophils and macrophages in burn wounds up to 46 days after injury implicate a persistent ongoing acute inflammation locally in the burn wound up to weeks after the initial trauma.