Sacks D L, Hieny S, Sher A
J Immunol. 1985 Jul;135(1):564-9.
Differentiation of Leishmania major promastigotes from a noninfective to an infective stage has been demonstrated for promastigotes growing within axenic culture and within the sandfly vector. We have been attempting to identify specific biochemical or antigenic changes that are associated with the development of infective-stage promastigotes. In this report we demonstrate that during growth, cultured L. major promastigotes undergo selective changes in surface carbohydrates, determined by their agglutination by plant lectins. Thus, although all promastigotes from logarithmic (log)-phase cultures were agglutinated by the two-D-galactose-binding lectins, peanut agglutinin (PNA) and Ricinus communis, identical concentrations of these lectins failed to agglutinate approximately 50% of L. major promastigotes from the stationary-phase cultures. These changes in lectin-agglutinating properties are consistent with the fact that log-phase promastigotes represent a homogeneous population of noninfective parasites, whereas up to 50% of the stationary-phase organisms appear to be transformed into infective-stage promastigotes, as determined by their ability to survive within normal resident mouse peritoneal macrophages in vitro. The identities of the populations defined by infectivity and PNA agglutination were confirmed by the purification of PNA-unagglutinated promastigotes from stationary-phase cultures, which demonstrated that 100% of these promastigotes were able to establish intracellular infections. Lectin-purified, infective-stage promastigotes from the stationary phase were compared with noninfective promastigotes from the log phase for the purpose of identifying stage-specific antigens. On the basis of Western blot analysis and the immunoprecipitation of surface-labeled organisms, we have identified an antigen of roughly 116,000 Mr that is expressed on the surface of infective but not noninfective promastigotes.
已证明，在无细胞培养物和白蛉媒介体内生长的硕大利什曼原虫前鞭毛体可从非感染阶段分化为感染阶段。我们一直在试图确定与感染阶段前鞭毛体发育相关的特定生化或抗原变化。在本报告中，我们证明，在生长过程中，培养的硕大利什曼原虫前鞭毛体表面碳水化合物会发生选择性变化，这可通过植物凝集素对其凝集作用来确定。因此，尽管对数期培养物中的所有前鞭毛体都能被两种结合D-半乳糖的凝集素——花生凝集素（PNA）和蓖麻凝集素凝集，但相同浓度的这些凝集素却无法凝集来自稳定期培养物的约50%的硕大利什曼原虫前鞭毛体。凝集素凝集特性的这些变化与以下事实一致：对数期前鞭毛体代表非感染性寄生虫的同质群体，而高达50%的稳定期生物体似乎已转化为感染阶段的前鞭毛体，这可通过它们在正常驻留小鼠腹腔巨噬细胞内体外存活的能力来确定。通过从稳定期培养物中纯化PNA未凝集的前鞭毛体，证实了由感染性和PNA凝集定义的群体的身份，这表明这些前鞭毛体中有100%能够建立细胞内感染。为了鉴定阶段特异性抗原，将稳定期凝集素纯化的感染阶段前鞭毛体与对数期非感染性前鞭毛体进行了比较。基于蛋白质印迹分析和表面标记生物体的免疫沉淀，我们鉴定出一种分子量约为116,000的抗原，该抗原在感染性而非非感染性前鞭毛体表面表达。
