Alegretti AP, Bittar CM, Bittencourt R, Piccoli AK, Schneider L, Silla LM, et al. Marseille, France) were: IgG1PE, CD45 FITC, CD117 PE, CD10 FITC, CD19 PE, HLA DR FITC, CD13 PE, CD33 PE, CD56 PE, CD3 FITC, CD7 PE, cTDT FITC, cMPO FITC, CD14 PE, CD15 FITC, CD34 PE, CD61 FITC and Glycophorin PE. Monoclonal antibodies were combined in the immunophenotypic panel, when necessary, especially to assess the following co- expressions: CD33/CD56/CD45, HLA-DR/CD56/CD45, CD117/CD56/CD45 and CD14/CD56/CD45. Schiff's reagent (Merck), erythrocyte lysis solution (FACS Lyse BD-Biosciences), perforating reagent Tween 20 (polyoxyethylene sorbitan monolaurate) and PBS solution (Na2H2PO .H2O, Na2HPO .NaCl) were used to prepare the 4 4 solutions necessary to carry out the technique. Results The AML subtypes of the 48 patients were classified according to the FAB group criteria. Eight patients (16.7%) were defined as being CD56 positive as this antigen expression was found on the surface of over 20% of the blast population in the sample. Among the CD56+ samples, the percentage of CD56 expression on blasts varied from 40.8 to 90.9% (mean: 67.4%). The age, gender and AML subtype of control patients (without CD56 expression) are listed in Table 1 along with the CD56+ cases. The median age of CD56+ patients was 53 years; none was aged 17 or under. The median age of the patients with no CD56 expression was 49 and eight (20%) patients were aged 21 or under. No significant age difference was identified between the groups (p-value = 0.301). The male:female ratio of CD56+ patients was 7:1 and 1.22:1 (22 males and 18 females) for those not expressing CD56. The proportions did not show any significant difference (Fisher's Exact Test: p-value = 0.123). A total of 62.5% of CD56+ patients died soon after or during induction compared with 27.5% of patients without CD56 expression. In spite of the observed tendency, there was no significant difference between the two groups (Fisher's Exact Test: p-value = 0.097). The difference between the OS of the groups was estimated using the Kaplan-Meier survival curve, comparing the survival of patients with or without CD56 expression using the Log-Rank test. As demonstrated in Figure 1, the time of OS was significantly shorter (p-value = 0.033) in CD56+ patients, with an average survival of 4.0 months (Range: 0.91 to 7.17 months; median: 1.0 month) compared to the mean survival of 14.5 months (Range: 10.0 to 18.9 months; median: 12.0 months) of patients with no CD56 expression. Figure 1 – Overall survival estimated using the Kaplan-Meier method in CD56+ (n = 8) and CD56- (n = 39) acute myeloid leukemia patients No studies were carried out to correlate CD56 expression and the rate and duration of complete remission, presence of extramedullary disease, resistance to multiple drugs, presence of genetic anomalies and investigation of aneuploidies through DNA analysis (phase S). Neither was the influence of other aberrant markers present in the immunophenotype investigated in respect to the induction death rate and OS. Discussion This study assessed a cohort of 48 patients admitted to HCPA, diagnosed as having AML and treated with standard chemotherapy protocols of the institution. The diagnosis was made based on clinical, cytomorphological, cytochemical and immunophenotypic data according to the FAB classification. Among the patients studied, 40 patients with no CD56 expression were considered a control group and eight CD56+ patients were considered the cases. 204 Rev Bras Hematol Hemoter. 2011;33(3):202-6