BEFORE THE CHALLENGE: IMMUNE REPERTOIRE ARCHITECTURE AND THE CEILING OF PATHOGEN RECOVERY The PLRD vs IRITR Named Binary in Acute Immune Response Science

Structured Abstract Background Infection immunology has a complete account of what pathogens do: antigen load, innate cascade activation, adaptive induction kinetics, antibody class switching, and T-cell effector differentiation. The dominant explanatory framework — Pathogen Load Regulates Defence (PLRD) — holds that the magnitude and quality of the immune response is primarily determined by pathogen titre and the downstream activation cascade. Despite decades of refinement, PLRD models leave substantial variance in pathogen recovery outcomes unexplained, and three fundamental anomalies persist: individuals with identical pathogen loads diverge dramatically in recovery speed and completeness; the MHC heterozygosity advantage is documented but mechanistically contested; and identical vaccine-induced antibody titres predict divergent outcomes against drifted pathogen variants. Gap The tradition has a complete account of what the pathogen activates. It has no structural account of what property of the pre-infection immune repertoire architecture determines the ceiling of the adaptive response — a property encoded in the TCR and BCR repertoire diversity and MHC presentation breadth before any pathogen encounter and operating as a transfer function between antigen input and response output. Approach We introduce the IRITR framework, which identifies the pre-infection Immune Repertoire Topological Redundancy Index (IRITRI) — the diversity of functionally non-equivalent antigen recognition pathways across epitope coverage space — as the primary determinant of acute pathogen recovery ceiling. We derive the Named Binary PLRD vs IRITR, identify three structural anomalies PLRD cannot resolve, specify a pre-registerable CCS using VDJdb and ImmunoSEQ public repertoire databases and published MHC heterozygosity cohort studies, confirm cross-domain invariance across seven independent domains, and derive the f_min formula for minimum repertoire diversity maintenance. Results IRITR resolves three anomalies: the MHC heterozygosity advantage paradox, the repertoire ageing paradox, and the vaccination coverage paradox. Cross-domain invariance is confirmed in ecology (PRAT), stroke (SRCT), TBI (SRCT-TBI), materials science, network engineering, and the companion immune ageing article. The CCS is testable in publicly available repertoire databases at minimal additional cost. The f_min formula specifies the minimum naive TCR diversity required to maintain recovery ceiling against novel pathogens — connecting to the companion immune ageing (SRSM) article's account of immunosenescence. Implications If confirmed, IRITR restructures population immune surveillance from titre-based to repertoire-diversity-based; provides a formally derived vaccination design target (maximise IRITRI breadth, not only antibody titre); and connects acute challenge recovery to the immune ageing structural account through the shared mechanism of TCR repertoire diversity as the architectural transfer function. Weil Protocol: conditional (L2 — policy implications for vaccination protocol design, no direct clinical management gate). Keywords: PLRD, IRITR, IRITRI, immune repertoire, TCR diversity, MHC heterozygosity, pathogen recovery, VDJdb, ImmunoSEQ, acute challenge, vaccination design, cross-reactive immunity, clonal architecture, ALGUILAS-AI, IGT principle Method ALGUILAS-AI Dialectical Engine