CD34 IMMUNOPHENOTYPING OF BLASTS IN MYELODYSPLASIAE

Immunological analysis of bone marrow cells in myelodysplasia using im munofluorescence did not allow accurate morphological identification o f blast cells. However, improvement of the immunoperoxidase technique allows one to realize the diagnostic potential of immunocytochemistry. CD34 immunotyping of blasts in normal human bone marrow showed 0.8 +/ - 0.4% CD34 positive blasts and these cells had the morphology of type 1 blasts. The increase of bone marrow blasts in RAEB patients is rela ted to CD34 negative type II and III blasts. A clone of undifferentiat ed CD34 positive blasts is characteristic of RAEB-T and acute myeloid leukaemia evolving from myelodysplasia. The detection of CD34 positive bone marrow blasts allows a better discrimination between RAEB and RA EB-T.