An immune molecule that appeared in evolution long before blood circulation may help improve cancer immunotherapy. Scientists at Nagoya University in Japan discovered that complement C3 can prevent immune-suppressing cells from building up inside tumors, but only when the protein is produced locally within the tumor. C3 traveling through the bloodstream did not influence how well treatment worked.
The findings, published in Nature Communications, suggest that reproducing this local effect could benefit patients whose tumors do not produce enough C3 naturally.
An Ancient Part of the Immune System
C3 is an evolutionarily ancient protein found even in simple animals such as sponges and jellyfish. Most C3 is made in the liver and released into the bloodstream, where it helps the immune system defend the body against infections.
Scientists know much less about what C3 does when it is produced directly inside tissues and organs.
