697

The 697 Cell Line with Early B-Cell Phenotypes

The 697 cell line consisted of medium-sized lymphoid cells with a large nuclear: cytoplasmic ratio. The nucleus was frequently indented and contained a fine chromatin network; nucleoli were not prominent (Fig. 1). Cytochemical studies showed that the 697 cell line was slightly positive for acid phosphatase and PAS, while it was negative for peroxidase and esterases. Vacuoles in the 697 cell line were shown to contain lipids by the oil-red-O stain. Cytogenetic studies demonstrated that the 697 cell line was pseudodiploid with a marker chromosome consisting of a translocation between chromosome 7 and 19: t (7;19) (q11; q13).

Results of immunologic and terminal transferase testing are summarized in Table 1. The 697 cell line was positive for CALLA and for the HLA-DR antigen. Furthermore, the 697 cell line expressed µ heavy chains but not light chains or any other heavy chain classes. Mu chains were easily detected by immunofluorescence in the cytoplasm, while the cell-surface staining for µ chain determinants was distinct but faint. Additional cell markers identified on the 697 cell line were a myeloid-macrophage antigen (MMA), the human natural killer cell antigen (HNK-l), and the transferrin-receptor antigen (T9). Enzymatic assay for TdT revealed 23 U/10⁸ cells for the 697 cell line. The 697 cell line was found to contain the Epstein-Barr virus nuclear and capsid antigens.

Fig. 1 Photomicrograph of leukemic lymphoblasts from cell line 697 showing prominent vacuolization (× 1000). (Findley HW Jr, et al., 1982)

Table 1. Phenotypic Features of Cell Lines 697. (Findley HW Jr, et al., 1982)

Bioluminescence Imaging of Leukemia Cell Lines in Vitro and Mouse Xenografts

Although animal models of leukemia often utilize survival time as the primary therapeutic endpoint, bioluminescence imaging (BLI) is increasingly being used to provide a quantitative and more rapid assessment of drug efficacy in pre-clinical oncology research. The utility of bioluminescence imaging (BLI) was investigated using firefly luciferase in monoclonal and polyclonal populations of leukemia cells in vitro and in vivo.

Polyclonal luciferase expressing populations of human T-cell ALL (Jurkat), B-cell ALL (697), and chronic myeloid leukemia (K562) cell lines were generated and luciferase activity was determined by measurement of bioluminescence intensity (photons/second) (Fig. 2). The maximum detectable bioluminescence intensity of the 697 cell line was 4.61 × 10⁶ ± 0.49 photons/second. The signal intensity increased to a maximum after injection of D-luciferin and then decreased slowly over time. The maximum signal intensity was reached between 9 and 16 minutes after the administration of D-luciferin and was also cell-line dependent.

Equal and comparable development of bioluminescence signal was also noted after transplantation of monoclonal populations of luciferase-transduced 697 cell lines in NSG mice (Fig. 3). After transplantation of luciferase-transduced 697 cells, the strongest bioluminescence signal in the liver and the femurs were measured.

Fig. 2 Dynamic change of the bioluminescent signal in leukemia cell lines (Jurkat, 697 and K562) 8 days post-transduction and Jurkat derivatives 18 days post-transduction. (Christoph S, et al., 2013)

Fig. 3 Pseudocolor images of two representative mice transplanted with monoclonal luciferase-expressing human leukemia cells (697). (Christoph S, et al., 2013)