Help - can someone explain antibodies please.

ian Lewin ian at ianlewin.freeserve.co.uk
Sun Nov 1 20:22:26 EST 1998


Aliging wrote in message <19981101130143.12509.00002302 at ng28.aol.com>...
>  Can someone explain what happens to the number of antibodies in the body
>during an infection? Does the number increase in order to fight the
infection
>or does the number decrease as they are used up fight ing the infection?
>
>Many thanks

>  Can someone explain what happens to the number of antibodies in the body
>during an infection? Does the number increase in order to fight the
infection
>or does the number decrease as they are used up fight ing the infection?
>
>

It depends on whether you have encountered the infective agent before or
not, either by vaccination or infection.

Assuming its your first contact the body responds roughly (there are always
exceptions) as follows....

Antibodies are  produced after roughly 5-7 days (which is why you get 7 day
flu), This antibody (called IgM) normally peaks after 10 days or so and
drops fairly rapidly. After 10-15 days another form of antibody is produced
(IgG) which can last for several months. During this period 'memory cells'
are formed which are stored ready and waiting for when the body contacts the
disease again (this is what should happen with vaccination).

When you contact the disease again you get a small reduction in the amount
of circulating antibody but very rapidly (within 2 days) large amounts of
antibody are produced by stimulation of the memory cells. This generally
works so well that the disease does not produce symptoms from a second
infection before it is cleared from the body.

Of course there are exceptions to this where a disease can evade the immune
system in various ways such as mutation, coating itself with polysaccharide
(the body cannot easily produce memory cells against sugars), and a myriad
of other ways some of which have yet to be fully understood like HIV.






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