Enzymes Histochemically Demonstrable in the Earliest Phase of Wound Healing

DURING my work on local reactions in acutely injured skin, I was attracted by the early appearance of certain enzymes in the healing wound. Most authorities consider that in wound healing there is initially a metabolically inert lag phase of 1–4 days duration. Relatively little is known about the first appearance of enzymes during this phase. Balazs and Holmgren 1 found alkaline phosphatase at the wound margin 24 hr. after the injury. Fell and Danielli 2 and Firket 3 demonstrated during the lag phase that this enzyme was only present in the invading polymorphonuclear leucocytes. Needham 4 considered that acid phosphatase probably plays no part in repair. To the best of my knowledge there has been no previous report of the distribution of leucine aminopeptidase during the lag phase of healing.