ESTABLISHMENT OF A LEUKEMIC-CELL LINE FROM A PATIENT WITH ACQUISITIONOF CHROMOSOMAL-ABNORMALITIES DURING DISEASE PROGRESSION IN MYELODYSPLASTIC SYNDROME

A cell line designated SKM-1 was newly established from leukaemic cell s of a 76-year-old Japanese male patient with monoblastic leukaemia fo llowing myelodysplastic syndrome (MDS). The cells were obtained from p eripheral blood of the patient when he lost multiple point mutations o f ras genes with acquisition of chromosomal abnormalities during disea se progression in MDS. The cells grew as a single floating cell, and h ave been continuously growing with the morphological characteristics o f immature monoblasts by serial passages during the past 42 months wit h a doubling time of about 48 h. By cytochemical analysis, the cloned cells were positive for butyrate esterase, but negative for the Epstei n-Barr virus associated nuclear antigen. Phenotypic analysis revealed the expression of myelomonocyte specific antigens such as CD4, CD13, C D33 and HLA-DR. Cells from the primary peripheral blood and those from 50 passages of the SKM-1 cell line both possessed no activated ras ge nes but showed karyotype abnormalities with 46,XY, del(9)(q13;q22), de r(17) t(17;?)(p13;?). The SKM-1 cells have two mutations in p53 gene a nd overexpress the p53 products. This cell line may contribute to a be tter understanding of molecular mechanisms in the progression from MDS to myelogenous leukaemia.