FacebookMail The human immune system is the most complex biological system we know, after the human brain. What happens when your body is invaded and your first lines of defenses are engaged in a fight for life and death? If you like this article, please sign up for Snapshot, Portside's daily summary. Email (One summary e-mail a day, you can change anytime, and Portside is always free.) Leave this field blank Science immune system biology
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