+C6d is a fragment of the [Complement system](/wiki/Complement) protein C6, appearing when this ancient immune cascade is activated. Its presence can be a subtle marker, signaling the body's defensive response in tissues or [Blood](/wiki/Blood). This molecule serves as a trace, hinting at an ongoing biological process.
+## See also
+- [C6](/wiki/C6)
+- [Immune System](/wiki/Immune_System)
+- [Inflammation](/wiki/Inflammation)
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