Recall T-cell response confirms immunogenicity of tungsten-induced rhEPO aggregates associated with PRCA. (A) T cells obtained from 3 patients treated with HX575 during the clinical trial INJ-17 were incubated with nonstressed or heat-stressed HX575, or TT as control. (B) PBMCs obtained from 3 patients treated with HX575 during the clinical trial INJ-17 were incubated with clinical lot A or B, or TT as control in a short-term PBMC differentiation assay²² ; a specific T-cell response shown as SI was calculated by a ratio of cell proliferation with individual stimuli divided by the cell proliferation with vehicle control; treatments were performed in an anonymized manner.