Arginase activity in human fibroblast cultures.

Controversial results have been published as to the presence of arginase activity in human skin fibroblasts in normal cells and in argininemia. Experiments were undertaken to see if arginase is intrinsic to the fibroblasts or may be there as the result of exogenous contamination inherent to the mode of cell culturing. The mode of harvesting by scraping or trypsin treatment demonstrated similar arginase activity. No significant differences of arginase activity were found between the fibroblasts grown on fetal calf or human serum. In the conditioned serum-free medium arginase separated on DEAE-cellulose into an A1 and A4 form. These fractions are identical with those found in the cells. Arginase activity varies, however, with age of the fibroblasts. These observations are also valid for fibroblasts from a case of argininemia. Arginase activity is therefore intrinsic to diploid human fibroblasts.