The Christian philosophers of the Middle Ages took up and developed this Aristotelean conception, making it one of the cardinal doctrines of Scholastic philosophy, the doctrine of modern Realism.

• 能够激活免疫系统的抗原需要具备以下条件：1、相对分子量大，表面抗原决定簇就多，而淋巴细胞要求一定数量抗原决定簇刺激才能活化；