I've not read it myself, but An Elegant Defense [1] by Matt Richtel has come highly recommended to me. My understanding is that it takes a more human-interest angle, but also does a good job explaining how the immune system works and how it can go wrong at a high level. May be worth checking out as well.

[1] https://www.goodreads.com/book/show/41806641-an-elegant-defe...