Specific antibody to recombinant DRS-1 in the serum of an AA patient. (A) Purified His-tag DRS-1, His-tag, and native DRS-1 were loaded in lanes 1, 2, and 3, respectively. Proteins were visualized using Coomassie blue staining. Blotted membranes were incubated with anti-His mAb, serum of a PNH⁺ AA patient, and serum of a healthy individual for detection of DRS-1 Abs. (B) An equal amount of purified His-tag DRS-1 protein was used to detect antibodies specific to DRS-1 in sera from 3 PNH⁺ AA patients (lanes 1-3), 3 PNH^– AA patients (lanes 4-6), 3 PNH^– MDS patients (lanes 7-9), and a healthy individual (Healthy).