The neutrophilic leukocyte in wound repair

The role of the neutrophilic leukocyte in wound healing was investigated by observing the progress of repair in the absence of these cells. Circulating neutrophils were eliminated in guinea pigs by the administration of antineutrophil serum (ANS) 24 hr before wounding and by daily injections throughout a 10 day period of healing. Control animals received normal rabbit serum at the same dose levels and times. The wounds consisted of six linear incisions in the dorsal skin of the animals.The contents of 24-hr neutropenic and control wounds were compared by quantitating the major cellular and extracellular wound components using a histometric technique. At 24 hr, there were no differences between control and neutropenic wounds in the per cent of total wound volume occupied by mononuclear leukocytes and fibrin. The neutropenic wounds had no neutrophils, had a significantly decreased volume of fluid space, and an increased volume of red cells, as compared with controls. The differences in numbers of erythrocytes and amount of fluid space in these two sets of wounds may be related to substances within neutrophils that promote lysis of erythrocytes or affect vascular permeability. In spite of the lack of neutrophils in the ANS-treated animals during the 10 days of healing, no differences were observed between the control and neutropenic wounds relative to the rate of wound debridement or the extent of repair. The wounds from the two groups of animals were identical in cellularity and degree of connective tissue formation. These observations support the notion that neither wound debridement nor the formation of granulation tissue are dependent upon the presence of neutrophils. A neutrophil response in early wounds is not an essential antecedent to the infiltration of monocytes, as suggested by previous investigations.