The early neutrophil infi ltrate scavenges cellular debris, foreign
bodies, and bacteria. Activated complement fragments aid in bacterial
killing through opsonization. The primary role of the neutrophil is
to sterilize the wound. The initial neutrophil infi ltrate is therefore
decreased in clean surgical wounds compared to contaminated or
infected wounds.
Within 2–3 days, the infl ammatory cell population begins to shift
to one of monocyte predominance (Fig. 3.2B). Circulating monocytes
are attracted and infi ltrate the wound site. These monocytes differentiate
into macrophages, and in conjunction with resident macrophages,
orchestrate the repair process.
Macrophages not only continue to phagocytose tissue and bacterial
debris, but also secrete multiple peptide growth factors, which activate
and attract local endothelial cells, fi broblasts, and keratinocytes to
begin their respective repair functions. Over 40 different cytokines
and growth factors are known to be secreted by macrophages (see
Table 3.1).
Depletion of monocytes and macrophages causes a severe alteration
in wound healing with poor debridement, delayed fi broblast proliferation,
and inadequate angiogenesis