A comparative study on lysosomal accumulation of gallium-67 and indium-111 in Morris hepatoma 7316A.

Intracellular localization of Ga-67 and In-111 was investigated in Morris hepatoma 7316A and in normal Buffalo rat liver cells by a cell fractionation method at 48 hr after an intraperitoneal injection of the nuclides. Lysosomal fractions of the tumor and normal liver cells had the highest relative specific radioactivities of the nuclides (p less than 0.001). In a gradual solubilization experiment, the release of the nuclides at the same time as the acid phosphatase from the lysosomal fractions (p less than 0.001) was thought to indicate that lysosomes are the site of accumulation for both nuclides whether in tumor or normal liver cells. Fragility of the tumor lysosomes might be inferred from the significantly greater regression coefficient in relation to the lysosomal fraction of tumor cells than that of normal liver cells when labeled with Ga-67 (p less than 0.001). The poorer confidence limit for the regression coefficient in relation to the lysosomal fraction of tumor cells labeled with Ga-67 seemed to indicate that Ga-67 determines lysosomal functions of tumor cells more precisely than In-111.