The influence of selected inhibitors of protein synthesis on the in vitro differentiation of mouse mononuclear phagocytes has been investigated. DL-p-Fluorophenylalanine at concentrations of 250 µg/ml inhibits the formation of three lysosomal hydrolases, cytochemically demonstrable acid phosphatase and osmiophilic, phase-dense granules. These effects occur in the absence of cell death and are reversed by L-phenylalanine. Puromycin at concentrations of 0.2 to 0.4 µg/ml has a similar effect on both the morphology and biochemistry of cell maturation.
Colchicine at a concentration of 0.05 µg/ml inhibits the growth in cell diameter and has less of an effect on enzyme production.
Cells exposed to leucine-H3 for 2 to 3 minutes exhibit the localization of grains in the perinuclear-dense granule region. After an exposure of 60 minutes a similar localization is evident but with a correspondingly greater number of grains. A similar localization of grains occurs when choline-methyl-H3 is employed as a tracer. The data suggest the storage of newly formed protein and possibly phospholipid in the centrosphere region.