Novel B-cell precursor leukemia sister cell lines, NALM-33 and NALM-34, established from a patient with acute...

Two novel B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) cell lines, designated NALM-33 and NALM-34, were established from a 72 year-old male patient with ALL at relapse. Subcultures of each initial flask were first made after eight weeks of continuous incubation; thus, the two cell lines are simultaneous sister cell lines. The cells proliferate consistently singly and free-floating in suspension. They are negative for Epstein-Barr virus (EBV) infection by polymerase chain reaction (PCR) and are negative for mycoplasma infection. They have the morphological appearance of lymphoblasts with a scanty rim of cytoplasm, fine nuclear chromatin and distinct nucleoli. The primary leukemic blasts showed a common ALL phenotype with CD19+, CD10+, CD13-, HLA-DR+ and Igs-; the cell lines NALM-33/-34 display an identical immunophenotype. They fulfill "European Group for the Immunological Characterization of Leukemias (EGIL)" criteria as BCP leukemia B-II type. While the immunoglobulin heavy chain genes were found uniquely to be in their germline configuration, rearrangement of both kappa and lambda light chain genes was noted by Southern blot analysis. CDR-II detection by reverse transcriptase-PCR was also not detected. NALM-33/-34 did not respond significantly to the proliferative stimuli of various hematopoietic cytokines. In the cytogenetic analysis, they revealed the t(8;14)(q24.1;q32) with additional numerical and structural chromosomal abnormalities. The extensive immunological, cytogenetic and functional characterization of NALM-33/-34 suggests that these two novel cell lines may represent unique and relevant in vitro model systems for BCP-type leukemia cells.