Kellar K L, Bridges N B, Monroe M C, Bell B A, Callaway C S, Evatt B L
Division of Immunologic, Centers for Disease Control, Atlanta, Georgia 30333.
Exp Hematol. 1990 Oct;18(9):979-84.
The Belgrade (b/b) rat has severe hypochromic, microcytic anemia accompanied by mild thrombocytopenia and a 49% reduction in megakaryocytes (MKs). The platelet counts are decreased only 34%, but relative platelet size measured by two independent methods averages 50% greater than controls. Thus, the platelet mass of the b/b rat is within the normal range. The marrow MK progenitors (MK colony-forming units, CFU-MK) respond linearly to increased colony-stimulating activity in vitro, but they are reduced 68% and form smaller colonies than normal. Flow cytometric analysis of MK ploidy indicates that significantly more MKs are distributed into the low and high ploidy classes compared with the normal, and the mean ploidy is similar. The b/b rat maintains effective thrombocytopoiesis in spite of a severe reduction in MK progenitors, primarily by an increased rate of maturation of the endomitotic compartment. Iron treatment partially arrests the b/b anemia and is associated with a significant increase in CFU-MK, a normalized MK ploidy distribution, and a significant decrease in platelet size. The favorable response to iron therapy suggests that the megakaryocytopenia is secondary to the severe anemia and results from stem cell commitment to the erythroid lineage.
贝尔格莱德（b/b）大鼠患有严重的低色素性小细胞贫血，伴有轻度血小板减少，巨核细胞（MKs）减少49%。血小板计数仅降低34%，但通过两种独立方法测量的相对血小板大小比对照组平均大50%。因此，b/b大鼠的血小板量在正常范围内。骨髓MK祖细胞（MK集落形成单位，CFU-MK）在体外对增加的集落刺激活性呈线性反应，但数量减少68%，形成的集落比正常的小。对MK倍性的流式细胞术分析表明，与正常情况相比，分布在低倍性和高倍性类别的MK明显更多，平均倍性相似。尽管MK祖细胞严重减少，b/b大鼠仍能维持有效的血小板生成，主要是通过核内有丝分裂区室成熟率的增加。铁治疗部分缓解了b/b大鼠的贫血，并与CFU-MK的显著增加、MK倍性分布正常化以及血小板大小的显著减小有关。对铁疗法的良好反应表明，巨核细胞减少是严重贫血的继发结果，是干细胞向红系谱系定向分化的结果。
