Background: Chromosomal abnormalities, such as 13q deletion, are emerging as important prognostic factors in multiple myeloma. The availability of cy togenetic information has long been hampered by the low mitotic activity of the plasma cells. To obtain a direct assessment of the myeloma cells pathology in high purity cell population, we háve ušed magnetics-activated cell sorting in combination with intephase fluorescence in šitu hybridization. Design and subject: The study inclu-ded 40 patients with multiple myeloma. Methods and results: We ušed chromosomal G-banding and interphase in šitu hybridization on CDI38+ and CD138- cells after selection by magnetic-activated cell separation. Hybridization was perfor-med to detectthe 13ql4 deletion in unselected bone marrow cells and, in parallel, in CD 138+ enriched samples. The 13ql4 deletion was foundin 10 of 40 (25%) of bone marrow samples withoutcell selection andin 25 of 40 (62.5%) of samples with CD 138+enriched myeloma cells. Conclusions: Our results confirm ťhat immunomagnetic selection of CD 138+cells increa-ses the probability of detection of the 13ql4 deletion in bone marrow samples

        Key words: Multiple myeloma, magnetic-activated cell separation, interphase fluorescence in šitu hybridization, 13q 14 deletion