Role of lysosomes in gallium concentration by mammalian tissues

Two microanalytical methods, electron probe X ray analysis (E P M A) and ion mass analysis (I A M) were used to study gallium incorporation in normal tissues (kidney, liver, mammary gland, bone marrow, bone tissue) and in experimental tumors. The very high sensitivity of I M A makes possible the detection of very low concentration of gallium (1 ppm) with a spatial resolution of 0.5 micron, on the other hand, E P M A of lower sensitivity (100 ppm) makes possible the relation between the gallium concentration and the ultrastructure of the cell. It was shown that gallium is concentrated in the lysosomes of both types of tissues, where it is precipitated in an insoluble form. In addition, gallium is systematically combined with phosphorus in these precipitates. These observations suggest an active intralysosomal concentrating mechanism related to the presence of local phosphatase activity.