Discussion of the meaning of the word "pathogen"

What is it about?

The earliest definitions of "pathogen" go like this: "any disease-producing agent, especially a virus, bacterium, or other microorganism." The "especially" bit is redundant. It is merely an acknowledgement of the mass action distortion brought about by common usage. Whilst a pathogenic organism is, without question, a pathogen, a pathogen is not, without exception, a pathogenic organism. For example, asbestos is a pathogen. But modern definitions veer towards " a pathogen is a pathogenic micro-organism". This has created a corrupting blind spot that is obstructing a full understanding the "purpose" of an immune response.

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Why is it important?

Until you acknowledge that the immune system is primarily about recognising and responding to pathogenic events, (damage/disruption/debris - the latter dominantly self tissue debris) you will continue to perceive the immune system as, primarily, a bug hunting, chasing and killing mechanism. Micro-organisms are primordial food for amoebocytes (that includes phagocytes) and any "attack" on micro-organisms relies upon the enrolment of this primordial capability. However, damage is what primarily initiates the response to pathogens (by this I mean any disease-producing agent). This is essentially a tautology - a statement that is so obvious that we should not need to emphasise it; but we need to for we seem to be blind to it.

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