Page 101 - Binder2

Because the immune system is not a blunt instrument. It
doesn’t attack everything foreign. If it did, we’d die after
the first bite of food. Or collapse in response to every
bacterial encounter on our skin. What makes the immune
system powerful isn’t just its ability to destroy. It’s its
ability to discriminate.

This ability is broadly named immune tolerance—the
learned and maintained state in which the immune system
deliberately ignores certain antigens, different from
tolerization which is a common term for immunogenicity to
drugs. Immune tolerance begins early and runs deep.

In the thymus, T cells are trained through central
tolerance. Cells that react too strongly to the body’s own
proteins are deleted. But not everything can be learned in
that early classroom. So the immune system relies on a
second layer: peripheral tolerance—a constant education
program that unfolds in the gut, the skin, the lungs, and
other barrier tissues. It’s here that the immune system
learns to ignore what it sees often, at low doses, and in the
right context: food proteins, microbiota, environmental
exposures.

This is why oral exposure matters. Why mucosal immunity
matters. Why the route, dose, and frequency of exposure
shape the immune system’s perception of risk.

When a molecule is introduced through the gut, it isn’t
simply digested—it’s evaluated. Specialized immune cells
stationed along the intestinal lining constantly monitor
what passes through. Chief among them are dendritic
cells—arguably the most intelligent and adaptive members
of the antigen-presenting cell family.

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