Dermal cellular inflammation in burns. an insight into the function of dermal microvascular anatomy

The damage caused by thermal trauma is augmented by the subsequent inflammatory response in a similar fashion to reperfusion injury. Animal studies have demonstrated a significant role for neutrophils in this delayed damage, but little is known about the numbers of neutrophils or other leucocytes that enter human skin following burns. We have longitudinally examined profiles of leucocyte migration into five cases of human partial thickness burns in relation to continued dermal microvascular destruction during the acute post-burn period. All burn wounds had a rapid influx of neutrophils that was followed by a delayed influx of macrophages. Compared to the controls, the two superficial burns also had rapid and sustained influx of CD4 and CD8 lymphocytes via patent post capillary venules in the dermal superficial vascular plexus, whilst in the three deeper burns, in which this superficial vascular plexus was occluded, the number of lymphocytes decreased. These results suggest that the patterns of leucocyte extravasation were dependent on the initial level of vascular occlusion, indicating that the dermal microvascular anatomy plays a pivotal role in determining the composition of the extravascular inflammatory cell infiltrates. The potential importance of this finding is highlighted by the differences in wound behaviour associated with the different leucocyte profiles.