This whole notion of “travelling inside a giant body”, and “being attacked by antibodies”, can’t help but evoke memories of Fantastic Voyage for me. I saw that film back in the 60s when I was a kid, and for me there were few (if any) other films of that day which could evoke such a sense of wonder — which of course was one of the major hallmarks of the Golden Age of Science Fiction.
It took a few more years before I grew old enough to fully appreciate Raquel Welch in that film, though… 😉