It`s the first time i`m using and ELISA kit. I understand how positive interferences can occur. But could anybody explain me how false negatives occurs? Thanks
In much the same way that you can get a false positive, an ELISA can result in a false negative under two general conditions. This applies pretty much whether you are dealing with a sandwich style ELISA (surface bound capture antibody --> antigen --> detection antibody [ --> optional second antibody to detection antibody for amplification of the signal]) or a bound antigen ELISA (antigen bound to surface --> detection antibody [ --> optional second antibody to detection antibody for amplification of the signal] ), assuming all other things are correct:
1. some substance in the solutions bind to the antigen of interest and thereby prevent the primary antibody from attaching to the antigen of interest.
2. some substance binds to the primary of secondary antibody thereby preventing the sandwich from forming.
Anything which prevents the antigen-antibody binding reaction will result in a false negative after washing as the unbound antibody and/or antigen will be lost during the wash procedure. And the same applies if the detection antibody is either unable to bind to the antigen (sandwich style) or the primary detection antibody.
Thaks a lot for your help!