SEM

The ALL Cell Line SEM With t(4;11) Chromosomal Rearrangement

A cell line, designated SEM, was established from the peripheral blood of a 5-year-old girl in relapse with t(4;11) ALL. During the first 8 months of culture, SK-HEP-1 hepatoma culture supernatant appeared necessary for the growth of SEM cells. During the first 8 months of culture, the doubling time of SEM cells was 7-10 d. After this period, the growth of SEM cells increased and the cell doubling time was approximately 48 h. Then SK-HEP-1 culture supernatant was omitted from the culture medium. The cell line has been propagated for more than 2 years in IMDM containing 10% FCS. SEM cell line was growing as single cell suspension and was found to be free of mycoplasma contamination and Epstein-Barr virus nuclear antigen.

SEM cells showed a lymphoblastic morphology with cell nuclei exhibiting one or more prominent nucleoli. Cells were pleomorphic in size and had cytoplasmic vacuolations (Fig. 1). Cytochemical staining of SEM cells revealed negativity for peroxidase. Sudan black, non-specific esterase activity and PAS reaction following staining results of the lymphoblasts of the patient. SEM cells were positive for TdT activity. Cytogenetic analysis of the SEM cell line was performed 5 and 10 months after the beginning of the culture. A t(4;11)(q21;q23), deletion of the short arm of chromosome 7 del(7)(p15), and deletion of the long arm of chromosome 13 del(13)(q12) were found as clonal karyotypic abnormalities (Fig. 2). Cytogenetic analysis of the leukemic cells from the patient's peripheral blood revealed identical cytogenetic abnormalities.

Fig. 1 Photomicrograph of SEM cells stained with Pappenheim's stain. (Greil J, et al., 1994)

Fig. 2 A representative karyotype of SEM cell line after GTG banding. (Greil J, et al., 1994)