Involvement of Notch-1 signaling in bone marrow stroma-mediated de novo drug resistance of myeloma and other malignant lymphoid cell lines

The bone marrow (BM) microenvironment plays a critical role in malignant cell growth, patient survival, and response to chemotherapy in hematologic malignancies. However, mechanisms associated with this environmental influence remain unclear. In this study, we investigated the role of Notch family proteins in myeloma and other malignant lymphoid cell line growth and response to chemotherapeutic drugs. All 8 tested cell lines expressed Notch-3 and Notch-4; 7 cell lines expressed Notch-1; and 6 expressed Notch-2 proteins. Interaction with BM stroma (BMS) activated Notch signaling in tumor cells. However, activation of only Notch-1, but not Notch-2, resulted in protection of tumor cells from melphalan- and mitoxantrone-induced apoptosis. This protection was associated with up-regulation of p21WAF/Cip and growth inhibition of cells. Overexpression of Notch-1 in Notch-1- U266 myeloma cells up-regulated p21 and resulted in protection from drug-induced apoptosis. Thus, this is a first report demonstrating that Notch-1 signaling may be a primary mechanism mediating the BMS influence on hematologic malignant cell growth and survival. (Blood. 2004; 103:3503-3510)

Immunocytochemical identification of meningeal leukemia and lymphoma: poly-L-lysine-coated slides permit multimarker analysis even with minute cerebrospinal fluid cell specimens

Use of immunocytology for accurate identification of malignant cells in cerebrospinal fluid (CSF) has so far been hampered by high cell requirements of the immunologic methods hitherto used. In an attempt to minimize cell loss in cytopreparation, electrostatic binding of cells to poly-L-lysine (PLL)-coated multispot slides, followed by immunocytochemistry, was investigated. Using optimized conditions of cell attachment and fixation and performing all washing procedures on the slide made multimarker analysis possible even in paucicellular specimens, while preserving excellent cell morphology and yielding high sensitivity in the detection of antigens. In a study of 26 CSF specimens with inconclusive cytomorphology, comprising 335 single marker determinations, we were able to discriminate reliably between resting or activated benign cells and a wide range of types of malignant lymphoid cell. A definitive diagnosis was reached in all cases by one tap only. Malignant meningitis was ruled out in ten specimens and proved in 16, including five in which the type of malignancy could only be determined by immunophenotyping. We conclude that immunocytochemistry on PLL-coated slides constitutes the method of choice for immunologic cell differentiation in CSF, which allows equivocal morphologic findings to be clarified.

Immunocytochemical identification of meningeal leukemia and lymphoma: poly-L-lysine-coated slides permit multimarker analysis even with minute cerebrospinal fluid cell specimens

Use of immunocytology for accurate identification of malignant cells in cerebrospinal fluid (CSF) has so far been hampered by high cell requirements of the immunologic methods hitherto used. In an attempt to minimize cell loss in cytopreparation, electrostatic binding of cells to poly-L-lysine (PLL)-coated multispot slides, followed by immunocytochemistry, was investigated. Using optimized conditions of cell attachment and fixation and performing all washing procedures on the slide made multimarker analysis possible even in paucicellular specimens, while preserving excellent cell morphology and yielding high sensitivity in the detection of antigens. In a study of 26 CSF specimens with inconclusive cytomorphology, comprising 335 single marker determinations, we were able to discriminate reliably between resting or activated benign cells and a wide range of types of malignant lymphoid cell. A definitive diagnosis was reached in all cases by one tap only. Malignant meningitis was ruled out in ten specimens and proved in 16, including five in which the type of malignancy could only be determined by immunophenotyping. We conclude that immunocytochemistry on PLL-coated slides constitutes the method of choice for immunologic cell differentiation in CSF, which allows equivocal morphologic findings to be clarified.