That makes me think of the "complement system" of innate immunity, where a collection of free floating proteins trigger and catalyze and assemble-with one anoth

That makes me think of the "complement system" of innate immunity, where a collection of free floating proteins trigger and catalyze and assemble-with one another in the presence of foreign material. https://en.wikipedia.org/wiki/Complement_system https://en.wikipedia.org/wiki/Complement_system