Leucine and alanine aminopeptidase activities in experimentally induced intradermal granulomas and late stages of wound healing in the rat.

The role of leucine and alanine aminopeptidases is studied in two discrete biologic systems: experimental late stages of wound healing and carrageenan-induced intradermal granulomas in the rat. In the wound healing rats, the proliferating granulation tissue and serum have high quantities of aminopeptidase activity which correlate positively with the degree of fibroblastic activity. Starch gel electrophoresis demonstrates that in fibroblasts there are at least three groups of aminopeptidases: two isoenzymes are secreted or released into the blood serum and the third is membrane bound in the cytoplasm. The carrageenan intradermal granuloma is an inflammatory reaction rich in mononuclear phagocyte cells and macrophages. Elevated tissue levels of aminopeptidases are directly related to the degree of cellularity of the granuloma. Serum aminopeptidase levels remain normal. Starch gel electrophoretic studies of the granuloma demonstrate that the tissue-bound isoenzyme is the main component. This study indicates that fibroblasts and macrophages produce different quantities of aminopeptidase isoenzymes. In the former they are released or secreted into the serum and in the latter they are membrane bound.