Philosophy of Biology: Immunology and individuality
Figures
![](https://iiif.elifesciences.org/lax/47384%2Felife-47384-fig1-v1.tif/full/full/0/default.jpg)
How immunology defines a biological individual.
According to the 'self-nonself' framework (left), the immune system is mainly a system for targeting and killing foreign bodies. Interfaces, such as the gut lumen, belong to the ‘outside’ of the organism, and boundaries are strict and fixed. According to the newly emerging 'immunological individual' framework (right), the immune system can eliminate self and nonself elements, it can tolerate self and nonself elements, but it also reinforces the cohesion between bodily constituents. In this framework, boundaries are constantly being redefined by the action of the immune system. Image credit: Wiebke Bretting (CC BY 4.0).
Tables
Different theories of immunogenicity.
The self-nonself theory and the discontinuity theory of immunity predict the same outcomes for persistent or slowly changing endogenous (self) elements, and also for suddenly appearing and/or rapidly changing exogenous (nonself) elements. The theories make different predictions for rapidly changing endogenous elements, and for persistent or slowly changing exogenous elements.
Motifs | Examples | Self-nonself theory | Discontinuity theory |
---|---|---|---|
Rapidly changing endogenous elements | - Some significant bodily transformations, when uncontrolled (e.g., puberty, metamorphosis, pregnancy) | tolerogenic response | effector response |
Persistent or slowly changing endogenous elements | - Usual functioning of the body | tolerogenic response | tolerogenic response |
Persistent or slowly changing exogenous elements | - Many components of the microbiota acquired early during ontogeny - Chronic viruses | effector response | tolerogenic response |
Suddenly appearing and/or rapidly changing exogenous elements | - Microorganisms that invade the organism suddenly - Most grafts | effector response | effector response |