Use of polyclonal anti-myeloperoxidase antibody in myeloid lineage determination.

This study reports the production of a rabbit polyclonal antibody to myeloperoxidase (MPO) and its use in ascertaining the myeloid lineage of blasts in leukaemia. Comparison of the immunocytochemical stain using the anti-MPO antibody with the routine cytochemical methodology showed that the former was more sensitive. In all subtypes of acute myeloid leukaemia (AML; 72 patients, M1-M6) greater number of MPO positive blast cells were observed by immunocytochemistry, the highest being in the promyelocytic leukaemia. It was also extremely specific for cells 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 12 patients of chronic myeloid leukaemia in blast crisis, blasts from 8 showed reactivity to this antibody and thus could be identified as belonging to the myeloid lineage and/or of the mixed blast crisis type.

Terminal deoxynucleotidyl transferase in acute leukemias by direct immunofluorescence.

TdT (terminal deoxynucleotidyl transferase) can be detected by radio enzymatic assay, biochemical assay in cell extracts, serum or plasma, and intracellularly in the smear by indirect immunofluorescent methods. The IgG fraction of anti-TdT serum is conjugated with fluoresceinisothiocyanate and used directly on the cytospin smears of methanol fixed bone marrow/blood smears. The mice thymocytes and peripheral mononuclear cells of healthy donors were used as positive and negative controls, respectively, for TdT. 64% of our cases of ALL were found to be TdT+. The lymphoblasts of L1 morphology (FAB classification) were more frequently positive for TdT as compared to blasts with L2 morphology. 71% of our cALLa positive blasts in acute lymphoblastic leukemias were TdT+ve as compared to 58% of T-ALL blasts. 75% of PAS positive ALL cases were positive for TdT as well. Only 57% of the cases when acid phosphatase showed unipolar positivity (T type) were positive for TdT. 12% of cases with acute myeloid leukemia (6/47) were TdT+ve and 33% of CML in blastic crisis had TdT+ve blasts. Biochemical assay and IF assay for TdT were in good correlation in our study.