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M Morimoto, T Kasugai, H Tei, T Jippo-Kanemoto, Y Kanakura and Y Kitamura
Department of Pathology, Osaka University Medical School, Japan.
The white-spotting (Ws) locus of rats represents a 12-base deletion of the
c-kit receptor tyrosine kinase. Homozygous Ws/Ws rats are deficient in
melanocytes, mast cells, and erythrocytes. Although mice possessing two
mutant alleles at the c-kit (W) locus, such as mice of W/Wv genotype, show
severe anemia even in adult age, the anemia of Ws/Ws rats remarkably
ameliorated with age. We investigated the mechanism of the age-dependent
amelioration. Bone marrow cells of Ws/Ws rats did not form macroscopic
colonies in the spleen of irradiated rats, and the concentration of
burst-forming unit-erythroid in the marrow of Ws/Ws rats was comparable
with that of +/+ rats. Therefore, the increase in morphologically
identifiable erythroid precursors in the marrow of Ws/Ws rats was
attributed to the increased concentration of colony- forming unit-erythroid
(CFU-E). Furthermore, the increase in CFU-E appeared to result from the
increased concentration of erythropoietin (EPO). Because injections of
relatively low doses of EPO cured the slight anemia that remained in adult
Ws/Ws rats, CFU-E and/or its immediate precursors of Ws/Ws rats appeared to
be more sensitive to EPO than those of W/Wv mice, in which a huge dose of
EPO was necessary to cure the anemia.
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| Copyright © 1993 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||