The body recognizes mold immediately as medicine is still catching up. Shoemaker named the chain reaction the Biotoxin Pathway, and it starts the moment your immune system identifies mold on contact.
Ribotoxins, mycotoxins, cell-wall fragments like β-glucans and chitin, even residual mold DNA bind specific pattern recognition receptors. Once those receptors trip, immune cells release inflammatory cytokines like IL-1β, TNF-α, and TGF-B1. They drive the "my PCP's labs were normal but I feel off" symptoms.
The lung takes the first hit because it's the first line of defense. Even inert particulate irritates alveoli. Immune cells arrive to investigate, become inflamed themselves, and re-enter circulation, carrying that inflammation everywhere else.
Continuous alveolar irritation reduces oxygenation. Tissue gets hypoxic. Hypoxia is itself inflammatory, and the loop tightens. Fatigue, brain fog, and exercise intolerance follow.
About 1 in 4 people have genetics that make clearing these biotoxins inefficient. For them, the pathway gets stuck on and MSH drops. When MSH drops, the inflammatory loop loses its brake.
That's when symptoms cross the formal CIRS threshold, and for others still in the same moldy building - they're on the curve of mold toxicity, just lower down.