title: QS-21 and QS-7: purified saponin adjuvants.
abstract: QS-21 and QS-7 are two adjuvant-active saponins that can be obtained in high purity from Quillaja saponaria Molina extracts. QS-21 is a highly characterized compound and is known to be a potent adjuvant for antibody and CD8+ CTL response to subunit antigens. Less is known about the activity and structure of the hydrophilic saponin QS-7. Hence, we have carried out a detailed structural and immunological characterization. As with QS-21, QS-7 was shown to be a 3,28-O-bisglycoside quillaic acid, with some differences being a higher degree of glycosylation and a considerably shorter fatty acyl unit in QS-7. These differences were correlated to a lower lytic activity against sheep red blood cells. Different doses of QS-7 were evaluated for stimulation of immune response to the antigen ovalbumin, given three times by subcutaneous route to C57BL/6 mice. QS-7 doses of 40 micrograms or higher were shown to induce a strong CD8+ CTL response reproducibly against E. G7-OVA targets (similar to that induced by a 5-10 micrograms dose of QS-21). QS-7 (at doses above 5 micrograms) was also shown to stimulate CTL against peptide 18 of HIV-1IIIB gp120 after three immunizations of Balb/c mice with recombinant gp120 and different doses of QS-7. These data suggest that a hydrophilic saponin with low lytic activity can stimulate MHC Class I CTL responses although a higher minimum dose may be required for some antigens.
authors.affiliation: Aquila Biopharmaceuticals, Inc., Worcester, MA, USA.
authors.forename: C R
authors.initials: CR
authors.lastname: Kensil
authors.forename: J Y
authors.initials: JY
authors.lastname: Wu
authors.forename: C A
authors.initials: CA
authors.lastname: Anderson
authors.forename: D A
authors.initials: DA
authors.lastname: Wheeler
authors.forename: J
authors.initials: J
authors.lastname: Amsden
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005260:Female; D015699:HIV Envelope Protein gp120 / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008956:Models, Chemical; D009828:Oleanolic Acid / Q000031:analogs & derivatives*; D010047:Ovalbumin / Q000276:immunology; D031990:Quillaja; D011994:Recombinant Proteins / Q000276:immunology; D012503:Saponins / Q000494:pharmacology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D015699:HIV Envelope Protein gp120; C112621:QS 7; D011994:Recombinant Proteins; D012503:Saponins; C078785:saponin QA-21V1; D009828:Oleanolic Acid; D010047:Ovalbumin