Research Institute for Health Sciences, Chiang Mai University, Chiang Mai, Thailand.
PLoS Pathog. 2010 Feb 19;6(2):e1000770. doi: 10.1371/journal.ppat.1000770.
Antibodies constitute a critical component of the naturally acquired immunity that develops following frequent exposure to malaria. However, specific antibody titres have been reported to decline rapidly in the absence of reinfection, supporting the widely perceived notion that malaria infections fail to induce durable immunological memory responses. Currently, direct evidence for the presence or absence of immune memory to malaria is limited. In this study, we analysed the longevity of both antibody and B cell memory responses to malaria antigens among individuals who were living in an area of extremely low malaria transmission in northern Thailand, and who were known either to be malaria naïve or to have had a documented clinical attack of P. falciparum and/or P. vivax in the past 6 years. We found that exposure to malaria results in the generation of relatively avid antigen-specific antibodies and the establishment of populations of antigen-specific memory B cells in a significant proportion of malaria-exposed individuals. Both antibody and memory B cell responses to malaria antigens were stably maintained over time in the absence of reinfection. In a number of cases where antigen-specific antibodies were not detected in plasma, stable frequencies of antigen-specific memory B cells were nonetheless observed, suggesting that circulating memory B cells may be maintained independently of long-lived plasma cells. We conclude that infrequent malaria infections are capable of inducing long-lived antibody and memory B cell responses.
抗体是自然获得性免疫的关键组成部分,这种免疫会在频繁接触疟疾后产生。然而,据报道,在没有再次感染的情况下,特定的抗体滴度会迅速下降,这支持了疟疾感染不能诱导持久免疫记忆反应的普遍观点。目前,关于疟疾是否存在免疫记忆的直接证据有限。在这项研究中,我们分析了生活在泰国北部疟疾极低传播地区的个体中针对疟疾抗原的抗体和 B 细胞记忆反应的持久性,这些个体已知要么对疟疾无免疫力,要么在过去 6 年内有过记录的恶性疟原虫和/或间日疟原虫的临床感染。我们发现,暴露于疟疾会导致产生相对强烈的抗原特异性抗体,并在很大比例的疟疾暴露个体中建立抗原特异性记忆 B 细胞群体。在没有再次感染的情况下,针对疟疾抗原的抗体和记忆 B 细胞反应都能稳定地维持很长时间。在一些情况下,血浆中未检测到抗原特异性抗体,但仍观察到抗原特异性记忆 B 细胞的稳定频率,这表明循环记忆 B 细胞可能独立于长寿浆细胞而维持。我们得出结论,偶尔的疟疾感染能够诱导长期的抗体和记忆 B 细胞反应。