If you are looking for the full text, it is most prominently featured in his primary publications and platform:
: A central practical pillar of his work involves maintaining a proper pH balance to ensure the "presence" of immune cells is effective. Blank, André Die Präsenz Des Immunsystems pdf
While a standalone PDF by that exact title is often sought in the context of his lectures or as part of his book Die Geheimnisse der Gesundheit , Core Concepts of "The Presence of the Immune System" If you are looking for the full text,