Novel B-Cell Precursor Leukemia Sister Cell Lines, NALM-33 and NALM-34, Established from a Patient with Acute Lymphoblastic Leukemia

Abstract

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 κ and λ light chain genes was noted by Southern blot analysis. CDR-III 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.

Key Words:

• Leukemia
• B-cell precursor ALL
• cell line