Adaptive value of polymorphism in intracellular self/not-self discrimination?

Area of Science:

• Immunology
• Evolutionary Biology
• Molecular Biology

Background:

• Pathogen adaptation relies on host uniformity, making host diversity a key defense mechanism.
• Major histocompatibility complex (MHC) polymorphism demonstrates the evolutionary advantage of non-uniformity in host defense.
• Previous theories suggested neutral mutations for non-MHC protein polymorphism, but this study proposes an alternative role.

Purpose of the Study:

• To explore the adaptive value of intracellular protein polymorphism beyond MHC.
• To investigate how protein polymorphism contributes to host defense against intracellular pathogens.
• To link protein polymorphism to a novel theory of self/not-self discrimination.

Main Methods:

• Theoretical analysis based on the differential aggregation theory of self/not-self discrimination.
• Application of the theory to explain the antigenicity of cancer cells and its extension to pathogen defense.
• Conceptual framework integrating protein polymorphism with intracellular immune responses.

Main Results:

• Intracellular protein polymorphism can recruit self-antigens into the antigenic repertoire of infected cells.
• These polymorphic self-antigens can function as "intracellular antibodies" by aggregating with pathogen proteins.
• Peptides from self-antigens or pathogen antigens presented by infected cells can be targeted by cytotoxic T cells.

Conclusions:

• Protein polymorphism, particularly in intracellular proteins, is of significant adaptive value for host defense.
• Polymorphism amplifies and individualizes the immune response to intracellular pathogens.
• This mechanism provides a dynamic and personalized defense strategy against microbial threats.