QS21
Encyclopedia
QS-21 is a purified plant extract that enhances the ability of the immune system
to respond to vaccine antigens. It is derived from the Soap bark tree
(Quillaja saponaria), which is native to the country of Chile
.
The extract contains water soluble triterpene
glucoside
compounds
, which are members of a family of plant-based compounds called saponin
s.
It is currently being tested as an Immunologic adjuvant
in various vaccine
s in attempts to improve their efficacy
. It is believed to enhance both humoral
and cell-mediated
immunity
.
QS-21 is currently under clinical evaluation as an additive for various trial vaccines, including those for HIV
, malaria
and cancer
. , it had been tested in more than 3000 patients in 60 clinical trial
s.
Immune system
An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
to respond to vaccine antigens. It is derived from the Soap bark tree
Soap bark tree
Quillaja saponaria, the soap bark tree or Soapbark, is an evergreen tree in the family Quillajaceae, native to warm temperate central Chile. In Chile it occurs from 32 to 40° South Latitude approximately. Populations are found even 2000 m above sea level. It can grow to 15-20 m in height...
(Quillaja saponaria), which is native to the country of Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
.
The extract contains water soluble triterpene
Triterpene
Triterpenes are terpenes consisting of six isoprene units and have the molecular formula C30H48.The pentacyclic triterpenes can be classified into lupane, oleanane or ursane groups.Animal- and plant-derived triterpenes exist, such as:*squalene...
glucoside
Glucoside
A glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes....
compounds
Chemical compound
A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...
, which are members of a family of plant-based compounds called saponin
Saponin
Saponins are a class of chemical compounds, one of many secondary metabolites found in natural sources, with saponins found in particular abundance in various plant species...
s.
It is currently being tested as an Immunologic adjuvant
Immunologic adjuvant
In immunology, an adjuvant is an agent that may stimulate the immune system and increase the response to a vaccine, without having any specific antigenic effect in itself. The word “adjuvant” comes from the Latin word adiuvare, meaning to help or aid...
in various vaccine
Vaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
s in attempts to improve their efficacy
Efficacy
Efficacy is the capacity to produce an effect. It has different specific meanings in different fields. In medicine, it is the ability of an intervention or drug to reproduce a desired effect in expert hands and under ideal circumstances.- Healthcare :...
. It is believed to enhance both humoral
Humoral immunity
The Humoral Immune Response is the aspect of immunity that is mediated by secreted antibodies produced in the cells of the B lymphocyte lineage . B Cells transform into plasma cells which secrete antibodies...
and cell-mediated
Cell-mediated immunity
Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages, natural killer cells , antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen...
immunity
Immunity (medical)
Immunity is a biological term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. The non-specific components act either as barriers or as eliminators of wide...
.
QS-21 is currently under clinical evaluation as an additive for various trial vaccines, including those for HIV
HIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
, malaria
Malaria
Malaria is a mosquito-borne infectious disease of humans and other animals caused by eukaryotic protists of the genus Plasmodium. The disease results from the multiplication of Plasmodium parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases...
and cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
. , it had been tested in more than 3000 patients in 60 clinical trial
Clinical trial
Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...
s.