Acceleration of the internalization of ligand-bound membrane DNA by thyroxine treatment in macrophages.

The localization of membrane DNA and the binding and internalization of DNase-colloidal gold complex were examined in mouse peritoneal macrophages in presence and absence of thyroxine (T4). Preexposure to the hormone for 5 to 10 min caused no change relative to the control but preexposures for 30, 60, and 90 min accounted for an increase in the ligand binding capacity, aggregation of the DNase-gold particles on the cell surface, and appearance thereof in coated pits, coated vesicles, smooth vesicles and, finally, inside lysosomes. After 30 min preexposure to T4, subsequent 10 min treatment with the DNase-gold complex was as effective as 1 h treatment had been without T4.