Does human DNA control the formation of antibodies?

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yimfong

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Does human DNA control the formation of antibodies? I think lymphocytes produce it when stimulated by antogens, is it right?
 

Pinkertinkle

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yimfong said:
Does human DNA control the formation of antibodies? I think lymphocytes produce it when stimulated by antogens, is it right?
B cells differentiate into plasma cells and produce antibodies if they recognize antigen with their plasma bound membrane antibody and recieve the proper costimulatory signal from a T cell or have enough cross linking of antigens. Each B cell expresses a membrane bound antibody that is specific for one antigen. This sequence of this antibody is not coded for in the genome, but arises from a series of DNA rearrangements.
 

mdsadler

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As B cells differentiate and mature they form their specific antibody (B cell receptor if attached to membrane) through gene recombination events. Basically there are many many gene segments and while producing the antibody only a few of these segments will be used. This recombination occurs randomly until the antibody is made. If a particular antibody (B cell receptor) happens to bind a particular antigen it will undergo hypermutation so that its affinity for that antigen increases. The antibodies are not made with a particular antigen in mind but are made randomly. The binding of antigen to one of these random antibodies then causes the B cell to remake the antibody so that it will bind more specifically.
 
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exmike

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at the most basic level, yes DNA controls the formation, but only in what the possible combinations are. No two people have the same antibody profile just no two people have the same DNA (except identical twins of course). This, along with other genetic determinants of immunity such as your MHC, minor histocompatibilty complex, and cell surface receptor profile determine your overall state of immunity. This is why some people are more susceptible to some diseases than others.
 

CalBeE

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Immunology is one of the most fascinating, but also most complicated field of Biological science out there... ;)
 

mlw03

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The paradigm of immunology is clonal selection. BEFORE antigen exposure, both B and T cells are specific for a particular antigen, and this is determined by the DNA rearrangements. Upon activation, the cells proliferate, and B cells will eventually differentiate into the antibody-secreting plasma cells. So the original poster kinda has it right, but you need to understand the whole mechanism for it to make sense.
 

rgporter

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yimfong said:
Does human DNA control the formation of antibodies? I think lymphocytes produce it when stimulated by antogens, is it right?
Pre-exising lymphocytes (plasma cells which used to be b-cells to be specific) produce antibodies. They are stimulated by encountering an antigen that is complementary to their unique antigen combining site or variable region.
As for the compostion of an Ig: One heavy chain bonds to one light chain to form an immunoglobulin subunit. Two of these subunits combine to form a traditional immunoglobulin. There are five classes of Ig's determined by their heavy chain (IgG, IgA, IgM, IgE, and IgD). These each have one of two types of light chains (kappa or lambda). There is approximately a 2:1 ratio of kappa Ig's to lambda Ig's in a non-pathogenic individual. In addition there are four subclasses of IgG and two of IgA. All of these classes and subclasses, which are controlled directly by genetic information, account for a small amount of the heterogeneity of your Ig's (there are around 10 million distinct combos I think) mostly it is caused by the variable regions (aka antigen combining site).

The specificity of the antigen combining site is determined by the combination of heavy and light chains in the Ig. The sequence of the heavy and light chains are determined by the DNA but their variability is complicated. The molecular mechanism for the viariability of the variable regions, I believe is unkown but some have postulated that it involves an error-prone DNA repair process.

Hope that helps and I hope I didn't make too many mistakes, I work for an immunologist but sometimes I let the theory slip as I get lost in the nuts and bolts of lab work.
 

W222

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RGPORTER SAID: "The sequence of the heavy and light chains are determined by the DNA but their variability is complicated. The molecular mechanism for the viariability of the variable regions, I believe is unkown but some have postulated that it involves an error-prone DNA repair process. "

WHAT YOU SAID IS WRONG: VDJ recombination takes place in both B and T cells. It is the process of genetic rearrangement that forms the heavy and light of Abs in B cells, it also forms the T cell receptor. V= variable, D = diverse, and J = joining. These are all genetic regions that code for different areas of the chains. These genetic regions are spliced and recombined to form an intact coding region that is transcribed/translated to form the Ab chains. The proteins that are mainly responsible for this process are the RAG1 and RAG2 proteins along with a number of splice/DNA repair proteins that are ubiquitosly expressed. There is also a process called Swith recombination that helps in self recognition but this is less understood and more complicated.
 

thewebthsp

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Viruses' hypervariable region ensures they mutate to possible evade the immune system, while plasma? cells likewise lose DNA error correction in an attempt to find an antibody which closely binds an antigen on the virus...

This is discrete math/probability, with the "winner" the one with the higher rate of combinations/time unit...

Obviously this doesn't cover macrophages, T cells, or MHCs....the immune system is an extremely tough cookie to figure out.
 
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