Figure 2.

Molecules that bind B7.1 can be isolated from plasma using CTLA-4 specific antibodies. CTLA-4 positive plasma, from subjects 19 (A), 22 (B), and 44 (C), were passed through a column linked to the CTLA-4 specific antibody AS32. Fractions, containing material that eluted from the column at low pH, were bound to 96 well plates and tested for interaction with various biotinylated proteins by ELISA: B7.1-Ig (gray bars), Muc-Ig (black bars), and the AS33 antibody (circles).