NY-ESO-1 antibodies in patients with prostate cancer. ELISA tests were performed with recombinant NY-ESO-1 protein as the antigen: Serially diluted sera from patients with NY-ESO-1 mRNA positive (filled square, open square) or negative (filled triangle, open triangle) tumors, positive control serum from an NY-ESO-1 positive malignant melanoma patient (cross), and negative control sera from healthy volunteers (filled circle, open circle).