The effect of L-leucine methyl ester on the phagocytosis and amino acid incorporation of murine peritoneal cells.

Murine peritoneal macrophages were treated in vitro with L-leucine methyl ester (0.25-5.0 mM). This treatment resulted in an inhibition of the amino acid incorporation into the cells both at 4 degrees C and 37 degrees C during a relatively short incubation period. The adherence of macrophages was not changed by the treatment. Bacterial phagocytosis was partly influenced: Leu-OMe did not change the binding but the engulfment of opsonized bacteria was blocked. Damage of the plasma membrane caused by Leu-OMe was not so serious as that produced by specific anti-PEC antiserum. Leu-OMe is a lysosomotropic agent accumulated preferentially by lysosomes. The vacuolization of the cells and the dilatation of the vacuoles are evidences for the intracellular damage. In the early phase this damage is characterized only by the leakage of the cytoplasm, later the damage of the plasma membrane can also be demonstrated.