User blog comment:Wrath022/Chapter 516: The Truth About Enchantment, Review/@comment-7418318-20170101085701/@comment-1776824-20170101203645

Because we know next to nothing about the antibodies except that they exist. We don't know if they are magic, or if they are something that latches onto the dragon slayer's actual body, or if they simply become one with their own Dragon Magic. With no way to isolate their location, or what they even technically are, there is no way for Irene to do anything about it since she had no clue they even existed, herself.