We pursue immunity-based systems based on the idea that the immune system solves the “self-nonself discrimination” problem, which could lead to a logical problem: that of self-reference. Consequently, we introduce a distributed system, which divides the system into units. However, this is not the end of the story. What makes the self-referential problem more complicated is that the immune system is not a closed system but is open to the environment. But it is this “openness” that the immune system takes full advantage of in solving the problem of self-nonself discrimination. Thus, in the framework of immunity-based systems, an adaptive system is introduced to allow the population-based and indirect transfer of information from the environment.