User blog comment:Dtar/Dragon Force Theory/@comment-30338537-20170109181143

It could be DF speeds up the growth of the Dragon Seed.

Would be hilarious if Acno got antibodies by eating Dragon souls and these souls created antibodies while being digested, even against the will of their (former) owners.

Perhaps it's also interesting to look at it from another perspective:

Normally a DS would become a real Dragon upon the maturation of the Dragon Seed. But those with antibodies can't become real Dragons and can at most achieve Dragon Force, a state close to the power of a real Dragon, but still below the real deal. Looking at it like this, one might say DF is the "nerfed" form of Dragonification. It leaves the DS weaker as he/she can't unlock his/her full potential, but allows the DS to keep his Human form.