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U.S.: Sea Sponge Helps Unlock Immune System Mystery |
| December 8, 2004 |
 | A type of sea sponge similar to the one pictured here helped researchers identify a cancer-fighting molecule.
Photo: NOAA |
A Japanese brewery, an Okinawan sea sponge, and some clever detective work have helped an international research team to solve a biological mystery, and the solution suggests a novel way to boost the body's defenses against cancer.
The team of scientists have found evidence that a sugary lipid (fat cell) called iGb3 plays a key role in regulating the response of natural killer T cells, a part of the immune system that plays an important role in preventing cancer and fighting infections.
Discovered less than 10 years ago, natural killer (NK) T cells are unusual because they target lipids (fat cells) rather than proteins. When a lipid signals a threat, NKT cells pump out chemical signals that tell other parts of the immune system to rid the body of these invaders. Scientists know a great deal about how the immune system recognizes proteins, but comparatively little about how the immune system identifies and deals with invading lipids.
Until now, the only substance known to fully activate NKT cells was a molecule derived from an Okinawan sea sponge Agelas mauritianus. In the 1990s, researchers at the Kirin Brewery in Japan found this molecule while performing a pharmaceutical screen for natural compounds with anti-tumor activity. The sea sponge molecule does not occur in mammals, but it pointed researchers toward similar molecules that do. Research with laboratory mice led the scientists to discover iGb3.
The discovery is a significant development in the search for a natural activator for NKT cells, which the scientists believe might be particularly valuable for preventing or treating cancers that spread to the liver, where NKT cells are most common. The study was published on November 11, 2004 in Science Express, the online early-publication version of the journal Science.
Source: University of Chicago Medical Center
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