Frequency of T-cell precursors specific to the DRS-1 epitope. (A) PBMCs of a DRS-1 Ab⁺ patient (pt 2), a DRS-1 Ab^– patient (patient 4; pt 4), and a healthy individual were subjected to ELISPOT assay using different combinations of APCs and DRS-1–derived peptides. (B) Another DRS-1 Ab⁺ patient (pt 3) was subjected to ELISPOT assay. The figure shows results of duplicate culture.