Albiti Anisa H, Nsiah Kwabena
Hematology. 2014 Apr;19(3):169-74. doi: 10.1179/1607845413Y.0000000113. Epub 2013 Nov 25.
Sickle haemoglobin (HbS) is known to offer considerable protection against falciparum malaria. However, the mechanism of protection is not yet completely understood. In this study, we investigate how the presence of the sickle cell trait affects the haematological profile of AS persons with malaria, in comparison with similarly infected persons with HbAA. This study is based on the hypothesis that the sickle cell trait plays a protective role against malaria.
Children from an endemic malaria transmission area in Yemen were enrolled in this study. Hematological parameters were estimated using manual methods, the percentage of parasite density on stained thin smear was calculated, haemoglobin genotypes were determined on paper electrophoresis, ferritin was measured using enzyme-linked immunosorbent assay, serum iron and TIBC were assayed using spectrophotometer, transferrin saturation index was calculated by dividing serum iron by TIBC and expressing the result as a percentage. Haematological parameters were compared in HbAA- and HbAS-infected children.
Falciparum malaria parasitaemia was confirmed in the blood smears of 62 children, 44 (55.7%) of AA and 18 (37.5%) AS, so there was higher prevalence in HbAA children (P = 0.047). Parasite density was lower in HbAS- than HbAA-infected children (P = 0.003). Anaemia was prominent in malaria-infected children, with high proportions of moderate and severe forms in HbAA (P = 0.001). The mean levels of haemoglobin, packed cell volume, reticulocyte count, platelets count, lymphocytes, eosinophils, and serum iron were significantly lower while total leukocytes, immature granulocytes, monocytes, erythrocyte sedimentation rate, transferrin saturation, and serum ferritin were significantly higher in HbAA-infected children than HbAS-infected children.
Infection with Plasmodium falciparum malaria caused more significant haematological alterations of HbAA children than HbAS. This study supports the observation that sickle cell trait seems to be a beneficial genetic factor that resists malaria, since inheriting it protects against significant haematological consequences of malaria.
已知镰状血红蛋白（HbS）能为抵御恶性疟原虫提供相当程度的保护。然而，保护机制尚未完全明晰。在本研究中，我们探究镰状细胞性状的存在如何影响患疟疾的AS个体的血液学特征，并与感染情况相似的HbAA个体进行比较。本研究基于镰状细胞性状对疟疾起保护作用这一假设。
来自也门疟疾流行传播地区的儿童参与了本研究。采用手工方法估算血液学参数，计算染色薄血涂片上的寄生虫密度百分比，通过纸电泳确定血红蛋白基因型，使用酶联免疫吸附测定法测量铁蛋白，用分光光度计检测血清铁和总铁结合力（TIBC），血清铁除以TIBC得出转铁蛋白饱和度指数并以百分比表示。对感染疟疾的HbAA和HbAS儿童的血液学参数进行比较。
在62名儿童的血涂片中确诊为恶性疟原虫血症，其中44名（55.7%）为AA型，18名（37.5%）为AS型，因此HbAA儿童的患病率更高（P = 0.047）。HbAS感染儿童的寄生虫密度低于HbAA感染儿童（P = 0.003）。疟疾感染儿童中贫血情况突出，HbAA型中中度和重度贫血比例较高（P = 0.001）。与HbAS感染儿童相比，HbAA感染儿童的血红蛋白、血细胞比容、网织红细胞计数、血小板计数、淋巴细胞、嗜酸性粒细胞和血清铁的平均水平显著降低，而总白细胞、未成熟粒细胞、单核细胞、红细胞沉降率、转铁蛋白饱和度和血清铁蛋白显著升高。
恶性疟原虫感染导致HbAA儿童比HbAS儿童出现更显著的血液学改变。本研究支持以下观点，即镰状细胞性状似乎是一种有益的遗传因素，可抵御疟疾，因为遗传该性状可防止疟疾造成显著的血液学后果。
