Population analysis of karyotypic heterogeneity of the Raji Burkitt lymphoma cell line. Analysis of 100 karyotypes.

A constant lymphoblastoid line Raji (Burkitt lymphoma) has been used as a model for population cytogenetic studies. In analyzing 100 G-banded metaphase plates, four karyotypically distinct clones of cells with 48 chromosomes have been recognized, forming a modal class. In tracing the origin of marker chromosomes (in all 15), the presence of material specific for Burkitt chromosome markers 14q+ and 8q- has been shown. The application of the method of karyotype reconstruction has shown a uniformity in the overall chromosome material of all four groups of cells despite a different set of normal and marker chromosomes. The presence of 40% of cells with unique structural rearrangements (USR) demonstrated, to a significant extent, the structural instability of chromosomes in Raji cells. The nonrandom nature of distribution of "hot spots" along the chromosomes in the process of formation of both markers and USR has been shown. A preferential involvement of chromosomes #6, #7, and #8, as well as of separate regions 1p32, 6q15, 11q13, and 21p13 has been recorded. This report discusses aspects of karyotypic heterogeneity of cell populations in vitro and structural instability of regions of chromosomes #1 and #11, that coincide with the localization of the oncogene L-MYC or sequence BLYM-1 and the oncogene BCL-1.