QS-21 is an immune-stimulatory saponin that can be used as an effective vaccine adjuvant[1]. QS-21 enhances vaccine immune responses by activating dendritic cells and helper T cells, promoting antibody production and cell-mediated immune responses[2]. QS-21 is an activator of the NLRP3 inflammasome and leads to subsequent release of caspase-1-dependent pro-inflammatory cytokines IL-1β and IL-18[3].
In vitro, QS-21 (2.5, 5, 25 μM) treatment of HUVEC and PBMC cells for 24 hours significantly reduced cell viability, with this cytotoxic effect being more pronounced in HUVEC cells[4]. QS-21 (0-50 μM) treatment of two human gastric cancer cell lines (SNU 1 and KATO III) and a normal human cell line (GES-1) for 24 hours resulted in dose-dependent toxicity in KATO III and SNU 1 cells, with IC50 values of 67μM and 13.6μM, respectively, but showed almost no cytotoxicity to GES-1 cells[5].
In vivo, immunization of mice with Aβ42 formulated with QS-21 adjuvant produced the highest antibody titers, followed by CFA/IFA > alum > TMG[6].
References:
[1] Marty-Roix R, Vladimer G I, Pouliot K, et al. Identification of QS-21 as an inflammasome-activating molecular component of saponin adjuvants[J]. Journal of Biological Chemistry, 2016, 291(3): 1123-1136.
[2] Welsby I, Detienne S, N’Kuli F, et al. Lysosome-dependent activation of human dendritic cells by the vaccine adjuvant QS-21[J]. Frontiers in immunology, 2017, 7: 663.
[3] Lacaille-Dubois M A. Updated insights into the mechanism of action and clinical profile of the immunoadjuvant QS-21: A review[J]. Phytomedicine, 2019, 60: 152905.
[4] Campos-Estrada C, Riquelme B, Vergara M, et al. In vitro Notch-mediated adjuvant immunogenic potency is induced by combining QS-21 and MPL in a co-culture model of PBMC and HUVEC cells[J]. Toxicology in Vitro, 2020, 68: 104947.
[5] Guzmán L, Villalón K, Marchant M J, et al. In vitro evaluation and molecular docking of QS-21 and quillaic acid from Quillaja saponaria Molina as gastric cancer agents[J]. Scientific Reports, 2020, 10(1): 10534.
Cribbs D H, Ghochikyan A, Vasilevko V, et al. Adjuvant‐dependent modulation of Th1 and Th2 responses to immunization with β‐amyloid[J]. International immunology, 2003, 15(4): 505-514.
QS-21是一种免疫刺激性皂苷，可用作有效的疫苗佐剂[1]。QS-21的作用是增强疫苗的免疫反应，它通过激活树突状细胞和辅助T细胞，促进抗体生成和细胞介导的免疫反应[2]。QS-21是NLRP3炎症小体的激活剂，并导致caspase-1依赖性促炎细胞因子I1-1β / I1-18的后续释放[3]。
在体外，QS-21（2.5, 5, 25μM）处理HUVEC、PBMC细胞24 h，显著降低了细胞存活率，这种细胞毒性作用在HUVEC细胞中更为明显[4]。QS-21（0-50μM）处理两种人胃癌细胞系（SNU 1和KATO III）和人正常细胞系（GES-1）24h，以剂量依赖性方式对KATO III和SNU 1细胞产生毒性作用，IC50 值分别为67µM和13.6µM，但是对GES-1细胞几乎没有细胞毒性[5]。
在体内，使用QS-21佐剂配制的Aβ42对小鼠进行免疫加强，产生的抗体效价最高，随后是CFA/IFA >明矾> TMG[6]。