In vitro effect of leucine-O-methylester on polymorphonuclear and mononuclear cells.

The uptake of Leu-OMe and Leu-Leu-OMe was studied in vitro in porcine PMN cells. Both methylesters are metabolized leading to the intracellular accumulation of leucine. Part of the hydrolyzed leucine gradually filtrates back into the culture medium in a time-, temperature- and methylester substrate concentration-dependent manner. Another portion of Leu-OMe is converted to Leu-Leu dipeptide. With respect to the cellular effects of Leu-OMe treatment ultrastructural studies showed the presence of large vacuoles without significant alteration of cell viability. Increased exocytosis of lysosomal enzymes did not lead to lytic events. Changes in the plasma membrane are indicated by the observation that Leu-OMe treatment causes the loss of the chemotactic activity to formyl-Met-Leu-Phe.