Ferreira M U, Kimura E A, Katzin A M, Santos-Neto L L, Ferrari J O, Villalobos J M, de Carvalho M E
Departamento de Parasitologia, Universidade de São Paulo, Brazil.
Ann Trop Med Parasitol. 1998 Apr;92(3):245-56. doi: 10.1080/00034989859807.
A critical role has been proposed for the switch from non-cytophilic IgG2 to cytophilic antibodies of IgG1 and IgG3 subclasses observed in the humoral immune responses to Plasmodium falciparum of some Africans. These Africans have acquired clinically immunity naturally, after several years of exposure to holo-endemic malaria. In the present study, the possibility that life-long exposure to low levels of malarial endemicity may be associated with changes in the IgG-subclass composition of antibodies to P. falciparum was investigated in a native Amazonian community. The subjects were 138 malaria-exposed but non-infected Karitiana Indians. In a separate investigation, the concentrations of IgG-subclass antibodies in acutely ill patients with severe malaria (N = 22) were compared with those in age- and sex-matched controls who had uncomplicated malaria (N = 44). Plasma concentrations of IgG against a detergent-soluble extract of P. falciparum schizonts were measured by quantitative ELISA, using indirect standardization. Among the Karitiana, the concentrations of anti-parasite antibodies of all subclasses increased with age, and there was no correlation between age and the proportion of such antibodies which was cytophilic. The predominance of cytophilic IgG1 and non-cytophilic IgG2 antibodies in all age-groups of the Karitiana provides an example of an intermediate pattern of immune responses to P. falciparum which contrasts with those previously described in both clinically immune and non-immune populations. Although mean concentrations of cytophilic IgG1 against P. falciparum were significantly higher in the controls than in the patients with severe malaria, there were no significant differences in other IgG subclasses. Lack of exposure to malaria in the past was associated with disease severity (odds ratio = 4.75; 95% confidence interval = 1.31-17.42), and may explain, at least partially, the occurrence of defective, low-IgG1 antibody responses to P. falciparum in those subjects who had severe malaria.
在一些非洲人对恶性疟原虫的体液免疫反应中，已观察到从非嗜细胞性IgG2向IgG1和IgG3亚类嗜细胞性抗体的转变具有关键作用。这些非洲人在数年暴露于高度流行的疟疾后，自然获得了临床免疫力。在本研究中，在一个亚马逊原住民社区调查了长期暴露于低水平疟疾流行环境是否可能与恶性疟原虫抗体的IgG亚类组成变化有关。研究对象为138名接触过疟疾但未感染的卡里蒂亚纳印第安人。在另一项调查中，将22名重症疟疾急性病患者的IgG亚类抗体浓度与44名患有非重症疟疾的年龄和性别匹配对照者的抗体浓度进行了比较。使用间接标准化法，通过定量ELISA测量针对恶性疟原虫裂殖体去污剂可溶性提取物的IgG血浆浓度。在卡里蒂亚纳人中，所有亚类的抗寄生虫抗体浓度均随年龄增加，且年龄与嗜细胞性此类抗体比例之间无相关性。卡里蒂亚纳所有年龄组中嗜细胞性IgG1和非嗜细胞性IgG2抗体的优势提供了一种对恶性疟原虫免疫反应的中间模式的例子，这与先前在临床免疫和非免疫人群中描述的模式形成对比。尽管对照者中针对恶性疟原虫的嗜细胞性IgG1平均浓度显著高于重症疟疾患者，但其他IgG亚类无显著差异。过去未接触过疟疾与疾病严重程度相关（优势比 = 4.75；95%置信区间 = 1.31 - 17.42），这可能至少部分解释了那些患有重症疟疾的受试者对恶性疟原虫产生有缺陷的低IgG1抗体反应的原因。
