From my naive point of view, there seems to be ambiguities in the question: say 1) the target for detecting antibodies is the peptide/peptide-cocktail or the cell/cell-mixture? 2) the nature of the experiment; 3) the purpose of the experiment; etc.

Before more information is supplemented, my answer would be: "in a way that would give you a high signal to noise ratio."

If you don't mind, may I have more information please?

Thank you very much in advance.

SOFA.