CYTOGENETIC STUDY OF 30 PATIENTS WITH MULTIPLE-MYELOMA - COMPARISON OF 3 AND 6 DAY BONE-MARROW CULTURES STIMULATED OR NOT WITH CYTOKINES BYUSING A MINIATURIZED KARYOTYPIC METHOD

Cytogenetics in multiple myeloma (MM) cases are generally difficult to perform due to the low proliferation index of malignant plasma cells (PC) in most cases. Although IL-6 and GM-CSF stimulate the in vitro pr oliferation of malignant plasma cells, their usefulness for improving cytogenetic results in multiple myeloma patients remains questionable, because results which compare various culture conditions in a suffici ent number of patients are not available. By using a miniaturized kary otypic method, we compared in 30 multiple myeloma patients the number and percentage of clonal abnormal mitoses obtained from 3 and 6 d bone marrow cultures performed without or with two combinations of cytokin es: IL-6 + GM-CSF or IL-6 + GM-CSF + IL-2 + IL-4 + TNF alpha. The perc entage of patients with an abnormal karyotype, which varied with the D urie and Salmon stage of the disease, as well as the type of numerical and structural karyotypic abnormalities that we detected, were in agr eement with published results. The detection of clonal karyotypic abno rmalities was better after 3 d of culture without cytokine than in all other culture conditions. The higher percentage of patients at all st ages of MM with an abnormal karyotype in our study (76 . 6%) than in p revious ones (20% to 60%) is largely explained by the large number of mitoses analysed in six different culture conditions due to the use of a miniaturized karyotypic method.