Mosser D M, Burke S K, Coutavas E E, Wedgwood J F, Edelson P J
Exp Parasitol. 1986 Dec;62(3):394-404. doi: 10.1016/0014-4894(86)90048-2.
The interaction of fresh serum with promastigotes of Leishmania major, L. donovani, L. mexicana mexicana, L. mexicana amazonensis, and L. braziliensis guyanensis results in lysis of all strains tested with either fresh human or guinea pig serum at 37 C for 30 min. Lysis does not occur in the cold and requires divalent cations and complement that is active hemolytically. Serum deficient in the eighth component of complement is not lytic. Lysis of L. major, L. mexicana, and L. braziliensis proceeds fully in human serum containing EGTA/Mg2+ or in guinea pig serum deficient in the fourth complement component. These species consume only small amounts of C4 from human serum and do not require calcium to optimally bind C3. The data indicate that all are activators of the alternative complement pathway and that the classical pathway is not required for the lysis of these organisms. Promastigotes of L. donovani, in contrast, activate the classical pathway. The presence of calcium is required for both optimal C3 binding and parasite lysis, and L. donovani promastigotes consume C4 when incubated in human serum. In high concentrations, human serum agglutinates all tested Leishmania spp. The agglutinating factor does not require divalent cations, is heat stable, and works at 4 C, suggesting that it is an antibody. This "naturally occurring" antibody cross reacts with all Leishmania spp. and agglutinates them. The adsorption of serum with any Leishmania species or with beads that are Protein A coated, removes the agglutinogen. This factor causes a slight enhancement in alternative pathway activation by L. major and mediates the classical activation by L. donovani. In adsorbed serum, L. donovani promastigotes only weakly activate the alternative complement pathway. Increased concentrations of adsorbed serum are therefore necessary for lysis to proceed. The titer can be partially restored by the addition of heat inactivated serum. Using purified components of the classical cascade, we are unable to visualize surface bound C3 on L. donovani promastigotes unless heat inactivated serum is also present. We conclude that all Leishmania spp. promastigotes are susceptible to lysis by normal serum independent of antibody. The presence of small amounts of naturally occurring antibody in human serum enhances the susceptibility of L. donovani promastigotes to lysis by activating the classical complement pathway.
新鲜血清与硕大利什曼原虫、杜氏利什曼原虫、墨西哥利什曼原虫墨西哥亚种、墨西哥利什曼原虫亚马逊亚种及圭亚那利什曼原虫的前鞭毛体相互作用，在37℃孵育30分钟时，无论是新鲜人血清还是豚鼠血清，均可使所有受试菌株发生裂解。在低温下不发生裂解，且需要二价阳离子及具有溶血活性的补体。缺乏补体第八成分的血清无裂解作用。硕大利什曼原虫、墨西哥利什曼原虫及巴西利什曼原虫在含EGTA/Mg2+的人血清或缺乏补体第四成分的豚鼠血清中可完全裂解。这些虫种仅消耗少量人血清中的C4，且不需要钙来最佳结合C3。数据表明，所有这些虫种都是替代补体途径的激活剂，裂解这些生物体不需要经典途径。相反，杜氏利什曼原虫的前鞭毛体激活经典途径。最佳结合C3及寄生虫裂解均需要钙的存在，杜氏利什曼原虫前鞭毛体与人血清孵育时会消耗C4。高浓度时，人血清可凝集所有受试利什曼原虫种。凝集因子不需要二价阳离子，耐热，在4℃起作用，提示它是一种抗体。这种“天然存在”的抗体与所有利什曼原虫种发生交叉反应并使其凝集。用任何利什曼原虫种或蛋白A包被的珠子吸附血清，可去除凝集原。该因子可使硕大利什曼原虫对替代途径的激活略有增强，并介导杜氏利什曼原虫的经典激活。在吸附血清中，杜氏利什曼原虫前鞭毛体仅微弱激活替代补体途径。因此，需要增加吸附血清的浓度才能发生裂解。通过加入热灭活血清可部分恢复效价。使用经典级联的纯化成分，除非也存在热灭活血清，否则我们无法在杜氏利什曼原虫前鞭毛体上观察到表面结合的C3。我们得出结论，所有利什曼原虫种的前鞭毛体均易被正常血清裂解，与抗体无关。人血清中少量天然存在的抗体通过激活经典补体途径增强了杜氏利什曼原虫前鞭毛体对裂解的敏感性。
