Endocytosis of the antiprotease aprotinin by Landschütz ascites carcinoma cells and its effects in vitro and in vivo.

Aprotinin was bound and endocytosed by Landschütz ascites carcinoma (LAC) cells in vitro. Addition of the antiprotease to cultures of these cells led to a dose-dependent growth-inhibitory and cytotoxic effect. In mice inoculated with LAC cells and treated with aprotinin there was a transient reduction in both the number and concentration of recovered ascites cells during the early phase of tumour growth. This was accompanied by a temporary increase in the proportion of peritoneal phagocytes (mononuclear phagocytes and polymorphonuclear leucocytes) relative to carcinoma cells. However, the number and concentration of ascites cells eventually achieved was comparable in saline and aprotinin-treated animals.