Immunotyping of blasts in refractory anaemia with excess of blasts

Abstract

A study of immunological markers was performed in 16 patients with newly diagnosed refractory anaemia with excess of blasts (RAEB) and RAEB in transformation (RAEB-T) and in 12 other patients with acute myeloid leukaemia evolving from RAEB or RAEB-T. Immunocytochemical investigation of bone marrow blasts was done using a modified indirect immunoperoxidase technique. This method permitted accurate morphological identification of blasts and other cells in bone marrow. The monoclonal antibodies used in RAEB and RAEB-T samples were anti-CD34, -c-kit, -HLA-DR and -CD13. The range of CD34 expression of blasts in RAEB samples was 1-14% (mean 6.2%) and in RAEB-T samples 29-48% (mean 35.5%). CD34 positivity was detected in 3-94% (mean 47.4%) of the bone marrow blasts in acute myeloid leukaemia evolving from RAEB and RAEB-T. Expression of c-kit was demonstrated only in a low percentage of blast cells in RAEB, RAEB-T and acute myeloid leukaemia following myelodysplasia. A high percentage (> 30%) of blasts in most patients with RAEB, RAEB-T and acute myeloid leukaemia was HLA-DR and CD13 positive. We observed the transformation from RAEB to acute myeloid leukaemia in three patients. The proportion of CD34 positive blasts increased to 25% and 32% in two patients. The third patient showed an unchanged percentage of CD34 positivity of blasts. These findings indicate that the CD34 positivity of blasts increases with the progression of myelodysplasia to RAEB-T and acute myeloid leukaemia demonstrating the instability of the clonal defect in myelodysplasia.

Diagnostic flow cytometry for low‐grade myelodysplastic syndromes

“…Stage I haematogones can be identified by their unique position on the SSC versus CD45 plot (Figure 1) or by their CD34þCD10þCD19þ/À phenotype. Relatively rare events that should be considered in their identification are that these cells show higher SSC than usual when they are duplicating and MDS myeloblasts from some patients show an aberrant CD34þCD10þ or CD34þCD19þ phenotype [41,42].…”

Immunotyping of blasts in human bone marrow

“…Immunophenotyping of blasts is essential to characterize the various subtypes of acute lymphoblastic leukemia and also certain types of acute myeloid leukemia using flow cytometry and immunocytochemical techniques [22]. Immunologic investigation of the small number of blasts in refractory anemia with excess of blasts (RAEB) and in RAEB in transformation was possible using an immunoperoxidase technique [23,24]. The bone marrow of healthy persons contains only a few blasts.…”

Clinical significance of phenotypic features of blasts in patients with myelodysplastic syndrome

“…In our own experience, reliable immunophenotype data for MDS blasts were obtained for only a fraction of MDS cases by flow cytometry (FCM). Hitherto, the available data on the MDS blast phenotype are for blasts of acute leukemia transformed from MDS (AL-MDS) 10 and blasts before leukemic transformation, 11,12 the latter of which were able to be analyzed only by immunocytochemistry and immunohistochemistry. Regarding the latter case, due to weaknesses of the applied techniques, the accuracy and objectivity of the data were not definitive and the number of antibodies used was small.…”