QS21

QS-21 is a saponin derived from the bark of the Quillaja saponaria tree, commonly known as the soap bark tree. It is used as an adjuvant in vaccines to enhance the body's immune response to an antigen. QS-21 has been used in vaccines for diseases such as malaria, HIV, and cancer.

History

QS-21 was first isolated from the bark of the Quillaja saponaria tree in the 1960s. It was initially used in veterinary vaccines, but its potential for use in human vaccines was soon recognized. The first human trials of QS-21 began in the 1990s.

Mechanism of Action

QS-21 works by stimulating the body's immune system to produce a stronger response to an antigen. It does this by activating immune cells such as T cells and B cells, which are responsible for recognizing and attacking foreign substances in the body.

Use in Vaccines

QS-21 has been used in a number of vaccines, including those for malaria, HIV, and cancer. It is often combined with other adjuvants to enhance its effectiveness. For example, in the Shingrix vaccine for shingles, QS-21 is combined with another adjuvant called MPL.

Safety and Side Effects

While QS-21 is generally considered safe, it can cause side effects in some people. These can include pain and swelling at the injection site, fever, and headache. In rare cases, severe allergic reactions can occur.

Future Research

Research is ongoing into the potential uses of QS-21 in other vaccines. It is also being studied for its potential use in treatments for allergies and autoimmune diseases.

See Also

• Adjuvant
• Vaccine
• Immune system
• Quillaja saponaria

QS21 Resources
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