labled antibody choice in elisa - (Jan/16/2010 )

Hi
I am going to set some elisa reactions with monoclonal anti his antibody, can I use directly labled anti his abtibody in elisa or I should use unlabled primary anti his antibody and labled secondary antibody, which ones leads to cleaner results?
best

In my experience it mostly makes no difference however theoretical the primary and secondary labeled system should give better results because the levels of aspecific binding would be lower.
when I start a new elisa i look at the antibodies that are already present at the lab and what is the most cost effective way to get the elisa working. This means most of the times I'll use a labeled primary antibody.