Effects of aging on the regulation of hematopoiesis among A-bomb survivors, 5

Stem cell colony formation was examined in 19 A-bomb survivors with myelodysplastic syndrome (MDS) and 12 non-exposed MDS patients. Among the A-bomb survivors, 9 had directly been exposed to the bombing and the 10 others had entered the city after the bombing. Leukemia developed in two patients in the exposed group and in 6 patients in the non-exposed group. According to the types of MDS, all of the patients in the directly exposed group had RAEB or RAEB-T. The incidences of PARA and PASA were significantly lower in the directly exposed group than the non-exposed group. (Namekawa, K)