2 dimensional DIGE comparison of plasma proteins that bind to either the CTLA-4 specific antibody AS32 or to an anti-MOPC isotype control antibody. Plasma containing molecules that react with the antibody AS32, as determined by ELISA, was passed over a column containing an anti-MOPC antibody. Flow through of that column was passed over a column linked to the antibody AS32. Both columns were washed in PBS, and bound material was eluted at low pH. Eluted fractions containing peak material were concentrated by binding to protein A beads and analyzed by 2 dimensional DIGE. Material that eluted from the anti-MOPC column was labeled with a green dye, and material that eluted from the AS32 column was labeled with a red dye. Yellow spots correspond to areas of the gel containing the same amount of signal from red and green labeled proteins.