Tissue iron deposition in untransfused beta-thalassemic mice

Homozygous β-thalassemic mice show many of the features seen in human β-thalassemia, such as decreased hemoglobin, hematocrit, and red blood cell count as well as increased reticulocyte count. They also exhibit splenomegaly and a decrease in osmotic fragility of red cells. β-thalassemic mice were examined for spontaneous iron overload at ages ranging from 20 to 595 days. Accumulation of iron was shown to occur in the spleen, liver, and kidneys but not in the heart. Sections of spleen, liver, kidney, and heart were stained for iron and subjectively scored. Image analysis microscopy was used to examine sections of spleen and liver. Nonheme iron in the four tissues was quantitated using the bathophenanthroline sulfonate colorimetric assay. An increase in tissue iron occurred primarily in the spleen, even before weaning, despite the low iron content of milk. Iron accumulation in the absence of blood transfusion is of interest because iron overload is the major cause of death in human β-thalassemia.