Franco R S, Barker-Gear R, Miller M A, Williams S M, Joiner C H, Rucknagel D L
Hematology/Oncology Division, University of Cincinnati College of Medicine, OH 45267.
Blood. 1994 Sep 15;84(6):2013-20.
A subset of sickle cells have an increased density at the reticulocyte stage of development, indicating that they are either abnormally dense upon release from the bone marrow or become dense quickly in the circulation. These cells are of interest because they most likely have severely disrupted cation regulation and a short lifespan. Based on the distribution of fetal hemoglobin (HbF) in the density fractions of sickle red blood cells (RBCs) and in vitro studies of cellular K+ loss, it seems likely that HbF content is an important in vivo determinant of dense cell formation. In this study, we tested the hypothesis that young, dense cells have low HbF content. Sickle RBCs were first separated into light and dense fractions. Reticulocytes were isolated from unfractionated cells and from each density fraction with an immunomagnetic technique directed against transferrin receptors (TfR) and assayed for the percentage of HbF and K+/Hb ratio. TfR+ reticulocytes isolated from unfractionated cells had a much lower HbF content when compared with all the unfractionated RBCs. This is most likely caused by enrichment of F cells because of a longer circulation life span. Heavy TfR+ reticulocytes had a K+/Hb ratio similar to that measured in the entire dense population and contained very low levels of HbF, averaging 2.5% of the level in all RBCs, 11.7% of the level in all TfR+ reticulocytes, and 4.0% of the level in all dense RBCs. These findings suggest that TfR+ dense cells derive predominantly from non-F cells. Furthermore, the amount of HbF in the circulating dense cells suggests that many of these cells do not derive from the TfR+ dense cells.
一部分镰状细胞在网织红细胞发育阶段密度增加，这表明它们要么从骨髓释放时密度异常，要么在循环中迅速变得致密。这些细胞备受关注，因为它们很可能严重扰乱了阳离子调节且寿命较短。根据胎儿血红蛋白（HbF）在镰状红细胞（RBC）密度分级中的分布以及细胞钾离子流失的体外研究，HbF含量似乎是致密细胞形成的一个重要体内决定因素。在本研究中，我们检验了年轻致密细胞HbF含量低这一假设。首先将镰状RBC分离为轻密度和高密度组分。用针对转铁蛋白受体（TfR）的免疫磁技术从未分级细胞以及每个密度组分中分离网织红细胞，并检测HbF百分比和钾离子/血红蛋白比值。与所有未分级的RBC相比，从未分级细胞中分离出的TfR +网织红细胞的HbF含量要低得多。这很可能是由于F细胞循环寿命较长而富集所致。重的TfR +网织红细胞的钾离子/血红蛋白比值与整个高密度群体中测得的比值相似，且HbF水平极低，平均为所有RBC中水平的2.5%、所有TfR +网织红细胞中水平的11.7%以及所有高密度RBC中水平的4.0%。这些发现表明，TfR +高密度细胞主要源自非F细胞。此外，循环中高密度细胞的HbF含量表明，这些细胞中的许多并非源自TfR +高密度细胞。
