A solid little CYOA. While I never saw OSMOSIS JONES, the premise seems similar--play a police-style commander taking care of disease and other trouble in a human body. Though the writing may not be ueber professional-quality, the author has fun drawing the personalities of different immune response characters.
With some background info (pop-up profiles of the characters, perhaps? Or some clearly-written science facts about them?) this could make a fun addition to a kids' classroom health unit. I know it's something I would've enjoyed as a kid.