Flow cytometric analysis of cell-surface antigen expressions on acute myeloid leukemia cell populations according to their cell-size

Cellular enlargement - A new hallmark of aging?

Years of important research has revealed that cells heavily invest in regulating their size. Nevertheless, it has remained unclear why accurate size control is so important. Our recent study using hematopoietic stem cells (HSCs) in vivo indicates that cellular enlargement is causally associated with aging. Here, we present an overview of these findings and their implications. Furthermore, we performed a broad literature analysis to evaluate the potential of cellular enlargement as a new aging hallmark and to examine its connection to previously described aging hallmarks. Finally, we highlight interesting work presenting a correlation between cell size and age-related diseases. Taken together, we found mounting evidence linking cellular enlargement to aging and age-related diseases. Therefore, we encourage researchers from seemingly unrelated areas to take a fresh look at their data from the perspective of cell size.

The importance of cell size and surface marker analysis in childhood acute myeloblastic leukemia

In order to evaluate the prognostic significance of cell size and surface marker expression, we evaluated 33 children with newly diagnosed acute myeloblastic leukemia by flow cytometry. We determined: the percentage of small, middle and large cells; large to small cell ratios (LS); large plus middle to small cell ratios (LMS); the percentage of surface markers expressed by each group of cell; the ratios of surface marker percentages expressed by the large blasts to that expressed by small blasts (LS for surface markers); and large plus middle blasts to that by small blasts (LMS for surface markers). For 'early prognosis', patients who could and could not achieve remission (n = 23 and 10) and for late prognosis, the patients who deceased or relapsed within the first 12 months of the treatment (n = 24) and who survived for more than 12 months (n = 9) were compared, in two classifications. CD3 percentages of the small cells of alive patients were significantly higher than that of dead or relapsed patients. LMS for CD3 and CD20 and LS for CD20 were higher in dead relapsed patients than that of alive patients. The total percentage of CD14 was significantly higher in dead relapsed patients than it was in the alive patients and CD3 was significantly higher in the group of patients who achieved remission than that of the patients who could not achieve remission. It was striking that, expression of CD3, CD7, CD22, CD33, CD14, CD15, CD34 increased or decreased as to cell size, whatever the prognosis. CD10, CD20 and CD13 were expressed on the large cells of the patients who could not achieve remission or died relapsed. We showed that, the blast cell size, individually does not have any prognostic significance in childhood AML and the prognostic significance of surface markers not only depends on their presence or absence but also on their relative configuration of expression by the blasts with different size.

Differentiation of leukemic cells induced by short-course high-dose methylprednisolone in children with different subtypes of acute myeloblastic leukemia

Differentiation of myeloid leukemic cells to mature granulocytes by high-dose methylprednisolone (HDMP, 20-30 mg/kg/day) with a favorable antileukemic effect has previously been demonstrated in children with acute promyelocytic leukemia and acute myeloblastic leukemia (AML) M4. In the present study, three children with other morphological subtypes of AML (two AML M1, one AML M2) were given methylprednisolone (30 mg/kg/day) orally in a single dose. After a short-course (3 or 7 days) of HDMP treatment alone, a striking decrease in blast cells associated with an increase in maturing and abnormally nucleated polymorphonuclear-like cells some containing Auer rods were detected in all patients in peripheral blood or bone marrow smears. During HDMP treatment, in parallel to morphological improvements, marked increases in the percentage of cells expressing granulocytic antigen (CD15) were observed. The increase of CD15 expression on myeloid cells, together with the steady expression of CD34 and CD117 antigens in Casel(AML M1) , is suggestive of aberrant CD34 + CD117 + CD15 + cells, which may indicate the leukemic origin of the maturing myeloid cells. These results suggest that HDMP treatment may induce differentiation of myeloid leukemic cells in some children with different morphological subtypes of AML, and that the differentiation-inducing effect of HDMP should be explored in other malignant diseases.

CD34+/CD33+ blast cells: correlation with FAB subtypes

The reproducibility of FAB morpho-cytochemical classification in a multicenter trial was recently assessed as 78.1%. The relevance of immunophenotyping in AML is debated because of the lack of a clear prognostic impact and the necessity of uniform diagnostic criteria and standardised methodologies. Several authors, studying the morpho-immunological characteristics of AML blasts by flow cytometry, suggested the necessity for the definition of clusters of cells with similar morphological patterns and intensity of expression. In this respect we reviewed blast CD34 and CD33 intensity of expression in 65 AMLs classified according to the FAB criteria. Four morphological groups could be identified: 1) low side scatter (SSC) and forward scatter (FSC); 2) intermediate SSC and FSC; 3) high SSC and FSC; 4) combination of pattern 2 plus 3. Five immunological patterns were defined: a) high CD34 expression with negative or weak CD33; b) high CD34 and CD33 expression; c) weak to negative CD34 with high CD33 expression; d) coexistence of 2 different subpopulations; e) negative to weak CD34 and CD33 expression. Based on this morpho-immunological analysis we were able to subdivide AML patients into 5 homogeneous subgroups and a comparison with FAB classification showed a concordance of 73.9%. Regarding CD34 and CD33 intensity of expression, a correlation with prognosis was demonstrated among all M1-M2 patients and in the M2 and M4 subgroups. In conclusion even if immunophenotype cannot substitute the FAB approach to AML, we feel that a flow cytometry morpho-immunological analysis could be helpful in achieving a greater understanding and agreement between different Institutions and assist in the definition of more precise prognostic subgroups.