CHROMOSOMAL AND IN-VITRO CULTURE STUDIES IN A CASE OF PRIMARY PLASMA-CELL LEUKEMIA

We present a cytogenetic study of a case of primary plasma cell leukem ia (PCL) whose plasma cells were cultured in vitro with different mito gens. Cytogenetic studies demonstrated a reduction of the genome, mono somy of chromosomes 8, 13, and 22 being the most frequent. Neither str uctural changes nor marker chromosomes were observed. The hypodiploid karyotype was confirmed and confined to the neoplastic clone (lambda p ositive cells) by the MAC (Morphology, Antibody, Chromosome) method, w hich allows a simultaneous study of chromosomes, cell morphology, and immunologic phenotype. Stimulating the culture of plasmocytes in vitro with IL-6 + PHA, only normal metaphases could be obtained; on the oth er hand, a large number of abnormal metaphases were observed with the use of LPS as a mitogen. A surprisingly high yield of metaphases was o btained in this case, contrary to the rule in the in vitro growth of p lasmocytic proliferations. Possible explanations of this fact are cons idered.