I have been trying to develop an ELISA assay to identify the presence of the whole parasite in culture by targeting one of its membrane protein. I recently found out that there is no signal difference between a culture medium containing my target cells and a culture medium free of my target cells, I used the medium as a control and it gave a high background (the medium composition RPMI, hypoxanthine,gentamycin an A+ human serum). I am suspecting, and my data suggests, that there might be a cross-reactivity between my antisera and the human serum, but I still can't figure out why. Any explanations?
Could it be that this cross reaction will prevent my antibody from reacting with the target protein on the surface of the parasites?