Chapter 39: Immune Systems: Self/Non-Self Recognition

The immune system is the body’s instantiation of the τ-Distinction predicate at the cellular level: every nucleated cell displays self-markers (MHC I) that the immune system reads, and antigen-presenting cells display captured fragments on MHC II for helper T cell inspection. Innate immunity provides fast, non-specific pattern recognition through Toll-like receptors, complement, and phagocytes. Adaptive immunity (T cells, B cells, antibodies) achieves highly specific distinction via V(D)J somatic recombination, generating {∼}10¹¹ unique receptor variants from {∼}400 gene segments. Autoimmunity—lupus, type 1 diabetes, multiple sclerosis, rheumatoid arthritis—is recast as formal distinction failure: the predicate D: X → 2_τ misclassifies self as non-self.