It's the way, for example, that foreign molecules or antigens get presented to cells of your immune system in order to start the process of making an immune response, so sometimes a cell/cell interaction.

通过这种方式,外源分子,或者说抗原,进入到免疫系统的细胞中后,就会开启免疫反应过程,有时候就是细胞之间的相互作用

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