Quantitative analysis of PDC-E2 antibodies in post-DLI, post-HSCT, MGUS, PBC, and MM patients compared with healthy donors. PDC-E2 antibodies were measured by ELISA in patient serum (1:100 dilution). Results are shown for 95 patient samples in 7 groups. The dashed line represents the cutoff limit based on the 95th percentile of reactivity in 52 healthy donors.