Question about The immune system.

[reyam200]

How does the body recognise a foren body, like a virus or bacteria.

is it because of a chemical signiture thats unique to that virus, or is it something else?

 

How do the Red Blood Cells carry oxygen?

[insane_alien]

1. chemical signals.

 

2. haemoglobin. the iron center binds with oxygen.

[reyam200]

ok,

 

cool, i thought it was iron that alowed oxygen to be carried. it only makes sence. iron binds with oxygen very easly.

[RyanJ]

ok' date='

 

cool, i thought it was iron that alowed oxygen to be carried. it only makes sence. iron binds with oxygen very easly.[/quote']

 

I believe insane_alien means the shape of the haemoglobyn molecule, this varies between species.

 

The chemical signals are parts that are extensions of the cells outer membrane called anti-gens. These are unique to you and to every other organism, this is the reason why blood groups are so important, giving someone the wrong type of blood, blood with the wrong anti-gen type and the immume system will start destroying the "invading" cells.

 

Cheers,

 

Ryan Jones

[ecoli]

First, I'd like to make sure you know that red blood cells have nothing (at least not directly) to do with the immune system.

 

1) there are cell receptors on White blood cells that enable the virus to recognize pathogens (there are some other threads on this, use the search function)

 

2) The iron is certainly important in binding oxygen, but the shape of the hemoglobin protein is also important.

[RyanJ]

First, I'd like to make sure you know that red blood cells have nothing (at least not directly) to do with the immune system.

 

Me? I do yes - I was just adding to what insane_alien said. I also used it ans an example for blood types because its a good common example

 

Cheers,

 

Ryan Jones

[Immunologist]

Your first question is quite large, but here is a good reference to start with:

 

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=pattern+recognition+AND+imm%5Bbook%5D+AND+125110%5Buid%5D&rid=imm.section.193#195

[Dr. Dalek]

If the cells can discern self from non-self based on surface molecules how do cells confuse self with non-self in autoimmune disorders?

[Nevermore]

Autoimmune disorders mess up the body's ability to descern between self and foregn objects.

[claytonm]

If the cells can discern self from non-self based on surface molecules how do cells confuse self with non-self in autoimmune disorders?

 

B cells undergo somatic hypermutation after Heavy and Light chain rearrangements when they leave the bone marrow and enter the periphery. This can lead to expression of self reactive Immunoglobulins. Also, T cells developing in the thymus may produce self reactive T cell receptors after Alpha and Beta chain rearrangement, and for one reason or another, fail to be clonally deleted.

[Steph]

B cells undergo somatic hypermutation after Heavy and Light chain rearrangements when they leave the bone marrow and enter the periphery. This can lead to expression of self reactive Immunoglobulins. Also, T cells developing in the thymus may produce self reactive T cell receptors after Alpha and Beta chain rearrangement, and for one reason or another, fail to be clonally deleted.

 

in other words... Upon generation, white blood cells can actually interact with anything. however, if they get too strong an interaction signal too early (meaning that they are reacting to something that's part of the self... usually) they will get shut down. when later on they get a moderately strong signal (which should be from a non-self particle... again, usually) they get to multiply. This is very simplified but even then you can see that these processes are far from being foolproof, which leads to the WBCs recognizing self particles as threats.

[Immunologist]

Autoantibodies and auto-reactive T cells are always generated in our body. But they are kept silent by 2 mechanisms. The first one involve not letting them out of their maturing organ (thymus): t cells that recognize self antigens (presented in the thymus) are sent in apoptosis (programmed cell death). In the periphery, if they were not killed in thymus, they are anergized by antigen presenting cells (APCs) if they recognize self-antigens (APCs do not express co-stimulation molecules necessary for activation).

So how can you have auto-reactive antibodies?

1. a self-antigen is expressed out of its context. Some proteins are expressed only in the eye, so are never presented as "self" in the thymus. But if someone get an injury to an eye and inflammatory cells can now get in the eye, they can be activated by these never-seen proteins.

2. Some proteins (antigens actually) are very similar to some pathogens, so after an infection, you get autoimmunity against your own self because it is similar to the previous infectious agent (see rheumatic fever with gr A b-hemolytic Streptcocci: http://www.life.umd.edu/classroom/bsci424/BSCI223WebSiteFiles/Chapter23.htm)

3. Also, in periphery, some cells are there to keep immune reactions low, the T regulatory cells (Treg). If for a reason or another, they do not perform their task, you can have autoimmunity.

 

4. Plenty of other known or still debated reasons.

Hope it helped.