[scientizscht (OP)]

Hello!

I know that antigens are broken down by antigen presenting cells and when a new antigen is presented, it triggers the creation of its antibody in immune cells.

1) how can the body produce antibodies for any antigen? how does the presentation of an antigen induces specific antibody creation?

2) how does the antibody created is engraved into the DNA of the bone marrow so that it gets repeatedly produced?

3) how does the presence of a specific antigen induces an over expression of that particular antibody?

4) does the immune system have a finite capacity of a maximum number of antigens it can recognize and process?

5) do all immune cells carry the same DNA and antibody range for all antigens known to that particular human or they specialise and if the latter how does this specialisation takes place?

Thanks!

[evan_au]

To start on (1): how can the body produce antibodies for any antigen?
It can't produce antibodies for every possible antigen.
- But it can produce antibodies for a wide variety of potential antigens
- The Major Histocompatibility Complex in DNA codes for some DNA regions that can be combined in multiple ways
- This generates a wide variety of chemicals that might bind to some future pathogen.
- If you have a very diverse MHC, then you can detect a wider range of pathogens, and it's less likely that you will come across a pathogen which is "invisible" to your immune system (and thus more likely to kill you)
- Inbreeding can result in a less diverse set of MHC regions
- There is evidence in mice that they prefer sexual partners with very different MHCs, which are likely to produce healthier offspring.

See: https://en.wikipedia.org/wiki/Major_histocompatibility_complex

I vaguely recall reading long ago that sharks have two hyper-variable regions, rather than 1 in humans. This allows them to generate a far larger number of matches to potential pathogens. This may explain why sharks are reportedly less likely to develop cancer?