Comparison of B7-1 and B7-2 detection on FL cells directly after isolation from a representative small cleaved follicular center cell lymphoma using fluorescence-activated cell sorter (FACS), immunocytology, or immunohistochemistry. (A) FACS analysis using directly fluorescein-labeled MoAbs for B7-1 and B7-2. Unshaded area indicates fluorescence of isotype-matched antibody. (B) Indirect FACS analysis using unlabeled MoAbs to B7-1 and B7-2 followed by goat-antimouse antibodies conjugated with PE. (C) Highly sensitive immunocytology using Vectastain ABC Elite reagents on cytospin preparations of freshly isolated FL cells. (D) Standard IH method (Vectastain ABC), and (E) highly sensitive IH (Vectastain ABC Elite) from the same FL sample in cryostat sections. Antibodies were used at optimal concentrations (see Table 1).