Proposal for the standardization of flow cytometry protocols to detect minimal residual disease in acute lymphoblastic leukemia.

Minimal residual disease is the most powerful predictor of outcome in acute leukemia and is useful in therapeutic stratification for acute lymphoblastic leukemia protocols. Nowadays, the most reliable methods for studying minimal residual disease in acute lymphoblastic leukemia are multiparametric flow cytometry and polymerase chain reaction. Both provide similar results at a minimal residual disease level of 0.01% of normal cells, that is, detection of one leukemic cell in up to 10,000 normal nucleated cells. Currently, therapeutic protocols establish the minimal residual disease threshold value at the most informative time points according to the appropriate methodology employed. The expertise of the laboratory in a cancer center or a cooperative group could be the most important factor in determining which method should be used. In Brazil, multiparametric flow cytometry laboratories are available in most leukemia treatment centers, but multiparametric flow cytometry processes must be standardized for minimal residual disease investigations in order to offer reliable and reproducible results that ensure quality in the clinical application of the method. The Minimal Residual Disease Working Group of the Brazilian Society of Bone Marrow Transplantation (SBTMO) was created with that aim. This paper presents recommendations for the detection of minimal residual disease in acute lymphoblastic leukemia based on the literature and expertise of the laboratories who participated in this consensus, including pre-analytical and analytical methods. This paper also recommends that both multiparametric flow cytometry and polymerase chain reaction are complementary methods, and so more laboratories with expertise in immunoglobulin/T cell receptor (Ig/TCR) gene assays are necessary in Brazil.

Proposal for the standardization of flow cytometry protocols to detect minimal residual disease in acute lymphoblastic leukemia

Minimal residual disease is the most powerful predictor of outcome in acute leukemia and is useful in therapeutic stratification for acute lymphoblastic leukemia protocols. Nowadays, the most reliable methods for studying minimal residual disease in acute lymphoblastic leukemia are multiparametric flow cytometry and polymerase chain reaction. Both provide similar results at a minimal residual disease level of 0.01% of normal cells, that is, detection of one leukemic cell in up to 10,000 normal nucleated cells. Currently, therapeutic protocols establish the minimal residual disease threshold value at the most informative time points according to the appropriate methodology employed. The expertise of the laboratory in a cancer center or a cooperative group could be the most important factor in determining which method should be used. In Brazil, multiparametric flow cytometry laboratories are available in most leukemia treatment centers, but multiparametric flow cytometry processes must be standardized for minimal residual disease investigations in order to offer reliable and reproducible results that ensure quality in the clinical application of the method. The Minimal Residual Disease Working Group of the Brazilian Society of Bone Marrow Transplantation (SBTMO) was created with that aim. This paper presents recommendations for the detection of minimal residual disease in acute lymphoblastic leukemia based on the literature and expertise of the laboratories who participated in this consensus, including pre-analytical and analytical methods. This paper also recommends that both multiparametric flow cytometry and polymerase chain reaction are complementary methods, and so more laboratories with expertise in immunoglobulin/T cell receptor (Ig/TCR) gene assays are necessary in Brazil.

Classification and clinical behavior of blastic plasmacytoid dendritic cell neoplasms according to their maturation-associated immunophenotypic profile.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare subtype of leukemia/lymphoma, whose diagnosis can be difficult to achieve due to its clinical and biological heterogeneity, as well as its overlapping features with other hematologic malignancies. In this study we investigated whether the association between the maturational stage of tumor cells and the clinico-biological and prognostic features of the disease, based on the analysis of 46 BPDCN cases classified into three maturation-associated subgroups on immunophenotypic grounds. Our results show that blasts from cases with an immature plasmacytoid dendritic cell (pDC) phenotype exhibit an uncommon CD56- phenotype, coexisting with CD34+ non-pDC tumor cells, typically in the absence of extramedullary (e.g. skin) disease at presentation. Conversely, patients with a more mature blast cell phenotype more frequently displayed skin/extramedullary involvement and spread into secondary lymphoid tissues. Despite the dismal outcome, acute lymphoblastic leukemia-type therapy (with central nervous system prophylaxis) and/or allogeneic stem cell transplantation appeared to be the only effective therapies. Overall, our findings indicate that the maturational profile of pDC blasts in BPDCN is highly heterogeneous and translates into a wide clinical spectrum -from acute leukemia to mature lymphoma-like behavior-, which may also lead to variable diagnosis and treatment.

Evaluation of annexin V and Calcein-AM as markers of mononuclear cell apoptosis during human immunodeficiency virus infection.

Evaluation of apoptosis by flow cytometry is generally accomplished by methods that use annexin V-FITC as vital dye, which access phosphatidylserine exposed on the external membrane at the beginning of this process. In addition, the concomitant use of propidium iodide makes possible to verify the characteristic nuclear alterations in the late stages of apoptosis, as a consequence of the increase in membrane permeability. On the other hand, the use of calcein-AM in association with ethidium homodimer (EthD-1) allows the evaluation of cell apoptosis through detection of esterase activity and cellular membrane physical and chemical alterations. The aim of this study was to compare the sensibility of calcein-AM and EthD-1 with annexin V-FITC and propidium iodide for early apoptosis evaluation in peripheral blood mononuclear cell culture, obtained from HIV-infected patients. Apoptosis and cellular viability were detected and quantified by flow cytometry after 24 and 48 hours incubation times. Our results showed that calcein-AM/EthD-1 was more sensitive for apoptotic cell quantification in both incubation times than annexin V-FITC/propidium iodide (mean of 46.95% +/- 3.56, p < 0.0001, for 24 hours and mean of 37.67% +/- 2.47, p < 0.0014 for 48 hours), besides allowing to clearly define viable, apoptotic and dead cell populations.

Evaluation of annexin V and Calcein-AM as markers of mononuclear cell apoptosis during human immunodeficiency virus infection

Evaluation of apoptosis by flow cytometry is generally accomplished by methods that use annexin V-FITC as vital dye, which access phosphatidylserine exposed on the external membrane at the beginning of this process. In addition, the concomitant use of propidium iodide makes possible to verify the characteristic nuclear alterations in the late stages of apoptosis, as a consequence of the increase in membrane permeability. On the other hand, the use of calcein-AM in association with ethidium homodimer (EthD-1) allows the evaluation of cell apoptosis through detection of esterase activity and cellular membrane physical and chemical alterations. The aim of this study was to compare the sensibility of calcein-AM and EthD-1 with annexin V-FITC and propidium iodide for early apoptosis evaluation in peripheral blood mononuclear cell culture, obtained from HIV-infected patients. Apoptosis and cellular viability were detected and quantified by flow cytometry after 24 and 48 hours incubation times. Our results showed that calcein-AM/EthD-1 was more sensitive for apoptotic cell quantification in both incubation times than annexin V-FITC/propidium iodide (mean of 46.95 percent ± 3.56, p < 0.0001, for 24 hours and mean of 37.67 percent ± 2.47, p < 0.0014 for 48 hours), besides allowing to clearly define viable, apoptotic and dead cell populations.

Effect of N-acetyl-L-cysteine on lymphocyte apoptosis, lymphocyte viability, TNF-alpha and IL-8 in HIV-infected patients undergoing anti-retroviral treatment

N-acetyl-L-cysteine (NAC) has been proposed as an additional therapeutic agent for AIDS patients because it reduces human immunodeficiency virus type 1 (HIV-1) replication in stimulated CD4+ lymphocytes, and it ameliorates immunological reactivity. In a randomized, 180-day, double-blind, placebo-controlled trial performed with HIV-infected patients classified as A2 and A3 according to the criteria of the Center for Disease Control and Prevention, we investigated the effects of oral administration of NAC on HIV-infected patients undergoing their first anti-retroviral therapy; viral load, CD4+ lymphocyte, lymphocyte viability and apoptosis, and TNF-alpha and IL-8 levels were determined. Sixteen patients who received anti-retroviral therapy plus a placebo formed the control group and the study group consisted of 14 patients who received anti-retroviral therapy and NAC supplementation. A significant decrease was seen in viral load, TNF-alpha and IL-8 levels, and lymphocyte apoptosis, and a significant increase was found in levels of CD4+ lymphocytes and lymphocyte viability in both groups after anti-retroviral treatment, but no measurable benefits of anti-retroviral therapy plus NAC oral supplementation (600 mg/day) were found in relation to anti-retroviral therapy alone, and the baseline levels of cysteine and glutathione in plasma were not recovered by this treatment. In conclusion, the daily doses of NAC necessary for the total recuperation of plasma cysteine and glutathione levels in HIV-infected patients and the additional benefits following the supplementation of NAC in patients submitted to anti-retroviral therapy, need to be studied further.

Effect of N-acetyl-L-cysteine on lymphocyte apoptosis, lymphocyte viability, TNF-alpha and IL-8 in HIV-infected patients undergoing anti-retroviral treatment.

N-acetyl-L-cysteine (NAC) has been proposed as an additional therapeutic agent for AIDS patients because it reduces human immunodeficiency virus type 1 (HIV-1) replication in stimulated CD4+ lymphocytes, and it ameliorates immunological reactivity. In a randomized, 180-day, double-blind, placebo-controlled trial performed with HIV-infected patients classified as A2 and A3 according to the criteria of the Center for Disease Control and Prevention, we investigated the effects of oral administration of NAC on HIV-infected patients undergoing their first anti-retroviral therapy; viral load, CD4+ lymphocyte, lymphocyte viability and apoptosis, and TNF-alpha and IL-8 levels were determined. Sixteen patients who received anti-retroviral therapy plus a placebo formed the control group and the study group consisted of 14 patients who received anti-retroviral therapy and NAC supplementation. A significant decrease was seen in viral load, TNF-alpha and IL-8 levels, and lymphocyte apoptosis, and a significant increase was found in levels of CD4+ lymphocytes and lymphocyte viability in both groups after anti-retroviral treatment, but no measurable benefits of anti-retroviral therapy plus NAC oral supplementation (600 mg/day) were found in relation to anti-retroviral therapy alone, and the baseline levels of cysteine and glutathione in plasma were not recovered by this treatment. In conclusion, the daily doses of NAC necessary for the total recuperation of plasma cysteine and glutathione levels in HIV-infected patients and the additional benefits following the supplementation of NAC in patients submitted to anti-retroviral therapy, need to be studied further.