PRTN3 and chronic myelogenous leukemia, BCR-ABL1 positive: It has also been reported that T cells specific for proteinase 3 (P3), a self antigen that is abundantly and exclusively expressed on normal myeloid cells, can emerge in CML patients under allogeneic BMT or interferon-α therapy but rarely in untreated patients; notably, the generation of these cells correlated with disease remission19.