USE OF POLYCLONAL ANTIMYELOPEROXIDASE ANTIBODY IN MYELOID LINEAGE DETERMINATION

This study reports the production of a rabbit polyclonal antibody to m yeloperoxidase (MPO) and its use in ascertaining the myeloid lineage o f blasts in leukaemia. Comparison of the immunocytochemical stain usin g the anti - MPO antibody with the routine cytochemical methodology sh owed that the former was more sensitive. In all subtypes of acute myel oid leukaemia (AML; 72 patients, M1 - M6) greater number of MPO positi ve blast cells were observed by immunocytochemistry, the highest being in the promyelocytic leukaemia. It was also extremely specific for ce lls of the myeloid lineage as it did not react with blasts from acute lymphoblastic (50 patients) and megakaryoblastic leukaemias (1 patient ). In addition, it proved most useful for the lineage determination of blasts from patients with undifferentiated acute leukaemias (AUL) and those with chronic myeloid leukaemia in blast crisis (CML-BC). Out of 8 patients of AULs, 6 were classified as acute myeloblastic leukaemia due to their reactivity to the anti-MPO antibody. Similarly, out of 1 2 patients of chronic myeloid leukaemia in blast crisis, blasts from 8 showed reactivity to this antibody and thus could be identified as be longing to the myeloid lineage and/or of the mixed blast crisis type.