How do Ab/Ag complexes trigger immune reactions?

[scientos]

Hello

When antibodies are floating, they do not trigger any immune reaction. However, when an antigen is bound to the antibody, then the resulting complex activates immune reactions.

How exactly these complexes trigger immune reactions? I think it is via their Fc fragment but what is the difference between a free antibody and an antibody with antigen bounded, so that the one does not trigger immune responses while the other does?

Thanks!

 

[poo thrower]

i dunno but according to wiki it is because a "free antibody" is un-fragmented, whereas a "antigen bounded" is "fc fragmented" which activates the FCreceptors resulting in response... (our bodys do not tell "pathogen", they tell "fragmented self").