Jensen J B, Vande Waa J A
Department of Microbiology and Public Health, Michigan State University, East Lansing 48824.
Vet Parasitol. 1988 Sep;29(2-3):171-7. doi: 10.1016/0304-4017(88)90124-0.
Crisis forms in malaria are degenerated intra-erythrocytic asexual parasites which appear at the time of immunologic crisis and thus may be part of the immune response to this disease. The factor(s) involved in this phenomenon are poorly understood, but are believed to be related to products of phagocyte activation. This hypothesis is supported by observations that animals, whose cell-mediated immune responses have been hyperstimulated by BCG, are protected from otherwise lethal malaria infections and their sera induce crisis forms in vitro. Many human serum samples collected from malaria-endemic areas of Sudan induce crisis forms in cultures of Plasmodium falciparum. Two popular models to explain this intra-erythrocytic, anti-parasitic action have been proposed: (i) the presence in the immune serum of a cytotoxic cytokine, crisis form factor, or (ii) that crisis forms result from oxidant stress generated during respiratory bursts associated with phagocyte activation, or indirectly by toxic products of lipid peroxidation produced by reactive oxygen species which appear in the serum during phagocyte respiratory bursts. Experimental evidence has been generated to support both of these hypotheses and both mechanisms may be involved in the induction of crisis forms.
疟疾危象是红细胞内无性繁殖期疟原虫的退化形式，出现在免疫危象时期，因此可能是对该疾病免疫反应的一部分。目前对这一现象所涉及的因素了解甚少，但据信与吞噬细胞激活产物有关。动物经卡介苗过度刺激细胞介导的免疫反应后可免受致命性疟疾感染，且其血清在体外可诱导危象形成，这些观察结果支持了这一假说。从苏丹疟疾流行地区采集的许多人血清样本可在恶性疟原虫培养物中诱导危象形成。人们提出了两种流行的模型来解释这种红细胞内抗寄生虫作用：（i）免疫血清中存在细胞毒性细胞因子、危象形成因子；（ii）危象形成是由于吞噬细胞激活相关的呼吸爆发过程中产生的氧化应激，或间接由吞噬细胞呼吸爆发时血清中出现的活性氧产生的脂质过氧化毒性产物所致。已有实验证据支持这两种假说，两种机制可能都参与了危象形成的诱导过程。
