netfunda Posted July 23, 2005 Share Posted July 23, 2005 Why is DNA not antigenic, while other macromolecules such as polysaccharides, proteins, etc. are antigenic? Link to comment Share on other sites More sharing options...
Bluenoise Posted July 23, 2005 Share Posted July 23, 2005 Well different DNA's from a molecular perspective are very simular. The possibility of having antigens produced that would recognise a unique DNA isn't very realistic, and if you recognised a small sequence it wouldn't be specific enough to be very useful. DNA just doesn't have the unique structural elements and functional groups need. Link to comment Share on other sites More sharing options...
Yggdrasil Posted July 23, 2005 Share Posted July 23, 2005 DNA is not antigenic because antibodies recognize antigens via specific structural features, and DNA fragments from different organisms are very structurally similar. For example, the sugar-phosphate backbone, on the outside of the DNA molecule, is identical in all DNA molecules. Only the base pairs differ between DNA molecules. Since the base pairs are sequestered within the interior of the DNA double helix, specialized structures are needed to access them. Proteins and oligosaccharides, on the other hand, have many structural features which an antibody can use to distinguish between native and foreign proteins/oligosaccharides. Link to comment Share on other sites More sharing options...
zyncod Posted July 23, 2005 Share Posted July 23, 2005 Well, actually DNA is antigenic in one sense. When the process of tolerance (killing autoreactive T and B cells) breaks down, like in lupus, the body can mount an immune response to DNA. But, like the other people said, the two- and three-dimensional structure of DNA is too similar to cause an antigenic response under normal circumstances. Link to comment Share on other sites More sharing options...
newty Posted August 10, 2005 Share Posted August 10, 2005 Although it is not quite antigenic, but there are plenty of bacterial strains that recognize methylated DNA and digest these DNA. Not an immunological response, just thought to be an host defense mechanism. Many of the restriction enzymes used in molecular biology work are sensitive to certain kinds of methylation. DNA itself is recognized and chewed up when cells spill out their guts (cell lysis), and there are signals that recognize this. As far as being antigenic in eukaryotes, I do not know. Newty Link to comment Share on other sites More sharing options...
Bluenoise Posted August 12, 2005 Share Posted August 12, 2005 Although it is not quite antigenic' date=' but there are plenty of bacterial strains that recognize methylated DNA and digest these DNA. Not an immunological response, just thought to be an host defense mechanism. Many of the restriction enzymes used in molecular biology work are sensitive to certain kinds of methylation. DNA itself is recognized and chewed up when cells spill out their guts (cell lysis), and there are signals that recognize this. As far as being antigenic in eukaryotes, I do not know. Newty[/quote'] Being a bit picky, but they recognize the non-methylated DNA. methylation usually prevents recognition. Link to comment Share on other sites More sharing options...
newty Posted August 12, 2005 Share Posted August 12, 2005 I stand corrected. Newty Link to comment Share on other sites More sharing options...
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