Neutrophils for example take up their "prey" in vacuoles and then merge those vacuoles with vesicles containing acid. In some form there is a "digestion" happe

Neutrophils for example take up their "prey" in vacuoles and then merge those vacuoles with vesicles containing acid. In some form there is a "digestion" happening. It's actually a non-trivial question to say if there is any form of energy that "escapes", for example in the form of keto-bodies, lipids, whatever, but it's certainly not very significant and certainly not the point of the digestion.