Myelopoiesis in myelodysplasia evaluated by multiparameter flow cytometry

Evaluating the proliferative activity of the immature erythro- and myelopoiesis as well as the mature myelopoiesis in 21 MDS patients and 14 healthy controls by simultaneously staining bone marrow cells for surface phenotype and DNA content, we found the percentages of proliferating S-phase cells in the early stage of MDS were higher. With disease progression evaluated by the FAB classification this parameter decreased significantly for both the immature myelo- and erythropoiesis. Evaluation of the proliferative activity of the mature myelopoiesis defined by the CD66 antigen revealed no difference between the normal controls and the MDS patients. Using another assay simultaneously labelling bone marrow cells for three leucocyte differentiation antigens during treatment with GM-CSF and low-dose AraC the cells clearly differentiated in one case. In another patient the disease seemed to progress as evaluated by cells only expressing immature antigens. The above mentioned immunophenotypic changes persisted at least one month after termination of treatment. In conclusion, the evaluation of proliferation and differentiation of leucocyte subsets using multiparameter flowcytometric assays in myelodysplastic patients from different FAB groups before as well as during treatment with haemopoietic growth factors may prove valuable in the future.