Establishment of a human megakaryoblastic cell line (T-33) from chronic myelogenous leukemia in megakaryoblastic...

A megakaryoblastic cell line, termed T-33, was established from the peripheral blood of a patient with Philadelphia chromosome-positive chronic myelogenous leukemia in megakaryoblastic crisis. T-33 cells have been maintained in RPMI 1640 medium containing 10% fetal calf serum in a single cell suspension with a doubling time of 24-36 h for over 2 years. Giemsa-banded karyotypes were female hyperdiploid with a modal chromosomal number of 51, all cells including Philadelphia chromosome. The cells showed strong positivity for periodic acid-Schiff and alpha-naphthyl acetate esterase, and weak for alpha-naphthyl butyrate esterase, but were negative for myeloperoxidase. Flow cytometric analysis of cell surface markers showed the existence of HLA-DR, MY-7, MY-9, and a platelet antigen (Yukb), and no markers for T- or B-lymphocytes. Most of the cells fixed with acetone were positive for Factor VIII, platelet glycoprotein IIb-IIIa, IIIa (Yukb), and Ib, but negative for glycophorin A and hemoglobin. Ultrastructural platelet peroxidase was demonstrated in 2-3% of cells and the percentage of positive cells increased up to 20% after the treatment with 12-O-tetradecanoylphorbol-13-acetate. The cells contained small dense granules negative for platelet peroxidase, their number increasing threefold after 12-O-tetradecanoylphorbol-13-acetate treatment. Such treated cells frequently showed a complex of the demarcation membrane in the cytoplasm. T-33 responded thrombin to exhibit calcium influx. This cell line may be useful for the study of the early stage of megakaryocytic differentiation in human megakaryopoiesis.