Monroy F P, Dusanic D G, Minning T A
Department of Life Sciences, Indiana State University, Terre Haute 47809, USA.
J Parasitol. 1998 Oct;84(5):914-9.
After elimination of Trypanosoma musculi from the general circulation by the immune responses of infected mice, the animals are resistant to reinfection. Yet, parasites survive in the vasa recta of the kidneys for the life of these mice. These kidney forms (KF) actively reproduce in an environment that provides the necessary nutrients and appears to prevent their elimination from these capillaries by the hosts' immune responses. Comparative studies conducted with KF and the bloodstream forms (BSF) indicate that, although both forms appear to be similar morphologically at the ultrastructural level, they differ in their surface reactivities with lectins and tolerance to various pH and solute concentrations. Although antibodies are not detected on the surfaces of KF, urea levels approximating those in the vasa recta dissociate antibody from the surfaces of BSF. The data suggest that parasites found in the vasa recta of these chronically infected mice differ from the BSF and are protected from the humoral and cell-mediated immune responses of the murine hosts by the concentrated solutes present in these capillaries. The KF may be killed by these same immune effector mechanisms upon leaving the capillaries of the kidneys and, therefore, not be found in the general circulation of these chronically infected immune hosts.
通过感染小鼠的免疫反应将鼠锥虫从全身循环中清除后，这些动物对再次感染具有抵抗力。然而，寄生虫在这些小鼠的肾脏直小血管中存活至其生命终结。这些肾脏型（KF）寄生虫在能提供必要营养的环境中活跃繁殖，并且似乎能阻止宿主的免疫反应将它们从这些毛细血管中清除。对肾脏型寄生虫和血流型（BSF）寄生虫进行的比较研究表明，尽管在超微结构水平上这两种形态看起来相似，但它们与凝集素的表面反应性以及对各种pH值和溶质浓度的耐受性有所不同。虽然在肾脏型寄生虫表面未检测到抗体，但接近直小血管中的尿素水平会使抗体从血流型寄生虫表面解离。数据表明，在这些慢性感染小鼠的直小血管中发现的寄生虫与血流型寄生虫不同，并且这些毛细血管中存在的浓缩溶质使其免受鼠宿主的体液免疫和细胞介导免疫反应的影响。肾脏型寄生虫一旦离开肾脏毛细血管，可能会被这些相同的免疫效应机制杀死，因此不会在这些慢性感染的免疫宿主的全身循环中被发现。
