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The article discusses the study of absence of BRAF mutation in hairy cell leukemia (HCL) cell lines with expressions of annexin A1 gene and B-cell receptor signals indicating its unrepresentative origins. The study comprised of evaluation of six HCL cell lines and their comparison with primary tumors. Western blot analysis confirmed four cell lines as positive for expression of annexin A1 gene.

In probing the cell of origin in malignant B cells, an imprint of somatic hypermutation (SHM) in immunoglobulin (Ig) variable (V) region genes delineates antigen encounter, and identifying the precise pathway generating SHM in the normal B-cell counterpart becomes relevant. SHM remains the definitive memory imprint in normal human B cells, but CD27 expression also delineates memory. Recently, dye extrusion adenosine triphosphate-binding transporter assays identified circulating isotype-switched memory B cells that lacked CD27, yet exhibited low levels of SHM. To extend findings, we report a pre-switched CD27−ve circulating memory B-cell population in normal blood using comparable assays, and isolated CD19+IgM+D+CD27−ve cells (>99% purity) for the analysis of IGHV5/IGHV3-IGHM transcripts. Of these (n=334), ∼78% were germ line and naive B cell derived. Strikingly, 21.9% of the transcripts were mutated. They showed 3–5 mutations (13.5% of sequences) and >5 mutations (8.4% of sequences) per transcript. Accrual of mutations in a subset of CD19+IgM+D+CD27−ve cells define a new circulating pre-switched memory B-cell pool, present in substantial numbers in the population harboring naive B cells. These CD19+IgM+D+CD27−ve memory B cells may have a distinct lineage and function, and seem relevant to understanding origins of malignant B cells, in particular those of hairy cell leukemia cells, which display mutated V genes yet lack CD27 expression. [ABSTRACT FROM AUTHOR]

Flow cytometric expression of bcl-2 protein was analyzed in 90 newly diagnosed acute myeloblastic leukemia (AML) patients using an anti-bcl-2 monoclonal antibody by direct immunofluorescence technique and results were correlated with FAB cytotype, CD34 expression and clinical outcome. Bcl-2 was expressed in all AML cases with different intensity. The mean fluorescence index (MFI), expressed as the ratio of sample mean channel:control mean channel, ranged from 3.0 to 39.5 with a median value of 14. The MFI was significantly higher (P = 0.01) in M0 (20.9) and M1 (18.3) than in M2 (11.7), M3 (12.4), M4 (11.8) and M5 (9.5) cytotypes. In addition, bcl-2 MFI significantly correlated both with CD34 positivity (P = 0.001) and with CD34 MFI (P = 0.01), being CD34 antigen expressed in 65% of patients with a bcl-2 MFI >14, and only in 35% of AML cases with a bcl-2 MFI >14. When bcl-2 intensity expression was correlated with complete remission (CR) rate, a higher MFI was associated with a low CR rate after standard intensive chemotherapy. In particular, CR was achieved in 86% of patients with a bcl-2 MFI <14, but only in 57% of patients with a MFI >14 (P = 0.008). A further decrease of CR rate to 41% was observed in patients in whom a higher bcl-2 MFI was coupled with the presence of CD34 antigen on their blasts. By statistical analysis we also demonstrated that both bcl-2 high MFI (>14) and CD34 expression are independent prognostic factors for achieving CR in AML. These data raise the hypothesis that high values of bcl-2 may confer on myeloid blasts a higher resistance to standard chemotherapy. However, identification of patients with high expression of bcl-2 may be important for a different therapeutic approach. [ABSTRACT FROM AUTHOR]

Between January 1991 and January 1994, 40 patients with hairy-cell leukemia (HCL), 30 males and 10 females, with a median age of 54 years, were treated with a single course of 2-chlorodeoxyadenosine (2-CdA) at a dose of 0.1 mg/kg/day continuous infusion for 7 days. Thirteen patients were untreated and 27 had previously received alpha-interferon. Thirty out of 40 patients (75%) achieved complete remission (CR) and 10 (25%) partial remission (PR). The median follow-up duration for patients in CR has been 48 months (range 30-66). Five of the complete responders (17%) relapsed at 12, 24, 26, 30 and 36 months after treatment as documented by the increase of hairy cells (Hc) in the bone marrow and two of them, who were retreated with 2-CdA after showing an initial impairment of peripheral blood values, obtained a second CR. The remaining three relapsed patients were never retreated and still show normal peripheral counts after 30, 38 and 40 months. Twelve of the continuous complete responder patients are still in CR after more than 5 years. In contrast, 8 out of 10 partial responders progressed after 8-36 months and all of them were retreated with 2-CdA at a dose of 0.15 mg/kg/day for 5 days i.v. Four of them (50%) achieved a CR, three a better PR and one patient died 6 months after the second 2-CdA course because of infectious complications. Two additional patients, both in CR, died after 28 and 37 months because of a second neoplasm. Toxic side-effects consisted of febrile episodes recorded in 16 patients: in seven of them, fever lasted only 24-48 h after the end of treatment and was apparently not infection-related. In the remaining nine patients, showing in addition severe neutropenia (neutrophils less than 1.0 x 10(9)/l), fever was related to bacterial infection requiring systemic antibiotics in all of them and G-CSF in three cases. In conclusion, 2-CdA induces a very high proportion of complete and long-lasting remissions in patients with HCL. In a number of cases relapse at bone marrow level may not affect peripheral blood values for prolonged time. However, in those patients with initial pancytopenia a retreatment with 2-CdA is still effective in inducing a durable second CR. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented about B-cell chronic lymphocytic leukemia that is published within the issue.

A letter to the editor about the impact of imatinib mesylate on specific anti-tumor T-cell in patients with chronic myeloid leukemia published online on November 10, 2005 is presented.

Presents a letter to the editor on the definition of somatic mutational status in B-cell tumors.