[thedoc (OP)]

Rod Kirkby  asked the Naked Scientists:
   Hi Chris. What particular characteristic of cells does the immune system use to decide 'self' from 'non-self'? I know it responds to foreign protein, but I presume it looks at specific markers on 'own' and 'foreign' protein. Given the above surmise, is there something about cartilage that makes it more difficult for the immune system to respond correctly, causing it to attack cartilage and cause rheumatoid arthritis? If so, could we do something to help the immune system to 'get it right', and stop attacking one's own cartilage? The same goes, of course, for other autoimmune diseases, but cartilage might make a good starting point to research the problem.


   
What do you think?

[evan_au]

Immune cells are trained in a child's Thymus gland so that any immune response to "self" tissues is suppressed.
See: https://en.wikipedia.org/wiki/Thymus

The immune system is often triggered by damage from an infection. The immune system learns characteristics of proteins and sugars found at the wound site - but sometimes these are proteins found in the victim's own body, and this can trigger an auto-immune attack.

You could start here: https://en.wikipedia.org/wiki/Autoimmunity#Treatments
https://en.wikipedia.org/wiki/Rheumatoid_arthritis#Management

The "Hygiene hypothesis" suggests that with modern "Western" medication (including soap, deworming tablets, sewage system and not having a dirt floor in your house), today's humans are not exposed to the same range of pathogens as our ancestors. This leaves the immune system with no real enemies to attack, so sometimes it turns on the patient.
It is known that some parasites produce chemicals which damp down the immune system (so the parasite isn't attacked). Some trials have been conducted of intentionally infecting patients with certain types of intestinal worms which damp down the immune system without causing any real harm to a typically over-nourished Westerner. If the intestinal worms don't help, they can easily be dispatched with deworming tablets.

But I would definitely check with your immunologist - the wrong kinds of parasitic worms can make the symptoms worse, or even kill you!

[AndroidNeox]

You might want to read about the major histocompatibility complex (MHC)