What Is-and What Is Not-Immunogenic Cell Death? Functional Definitions, Experimental Standards, and Common Pitfalls.

Area of Science:

• Immunology
• Oncology
• Cancer Research

Background:

• Immunogenic cell death (ICD) links tumor demise to anti-tumor immunity but suffers from inconsistent definitions and biomarker overinterpretation.
• Current understanding often conflates danger-associated molecular patterns (DAMPs), cytokine release, and endoplasmic reticulum stress with ICD itself.

Purpose of the Study:

• To propose a refined definition of ICD based on its functional immunological endpoint: efficient antigen presentation and antigen-specific adaptive immunity.
• To introduce a hierarchical framework for experimental validation of ICD, moving beyond correlative hallmarks.

Main Methods:

• Synthesis of mechanistic and methodological evidence.
• Development of a 4-level hierarchy for validating ICD: correlative hallmarks, innate immune integration, T-cell priming, and vaccination-rechallenge protection.
• Discussion of common pitfalls and essential immune-context controls (e.g., MHC-I, CD8+ T cells, dendritic cells).

Main Results:

• Danger-associated molecular patterns (DAMPs), cytokine release, and endoplasmic reticulum stress indicate immunogenic potential, not ICD directly.
• A proposed definition emphasizes efficient antigen presentation, antigen-specific adaptive immunity, and immunological memory as the functional endpoint of ICD.
• The hierarchical framework provides graded standards for robust ICD claims, including immune-dependence testing and human data.

Conclusions:

• ICD is context-dependent, influenced by dendritic-cell competence, innate licensing, metabolism, and the tumor microenvironment.
• Evidence-graded standards are crucial for improving reproducibility, peer review, and clinical translation of ICD-based cancer therapies.
• Refined definitions and validation methods will accelerate the development of effective ICD-based anti-cancer strategies.