Chromosome studies in stimulated lymphocytes of B-cell chronic lymphocytic leukemias

Using a sister chromatid differentiation technique, cell cycle study of stimulated lymphocytes of B-cell chronic lymphocytic leukemia (B-CLL) revealed their cell cycle progression to be similar to that of normal lymphocytes stimulated by T-cell and various polyclonal B-cell activators (PBA). The chromosome constitutions of stimulated lymphocytes in 62 patients with B-CLL were examined using PBA such as Epstein-Barr virus (EBV) and lipopolysaccharide W from E. coli 055:B5 (LPS). Of the 20 patients with abnormal clones, 11 patients had trisomy 12; other less common abnormalities were trisomy 1, 6q-, i(7q), 14q+, trisomy 16, trisomy 18, reciprocal translocations, and marker chromosomes of unknown origin. These findings indicate that trisomy 12 may be a unique and common karyotypic change in B-CLL. The fact that 3 out of 4 patients with marker chromosomes showed stage IV disease may indicate that a clone with a marker is a predictor of an unfavourable prognosis. The near correlation between trisomy 12 and kappa chains existed (0.05 less than p less than 0.10). Trisomy 12 was seen in all 5 patients with monoclonal paraprotein.