Chromosomal variability in ten cloned sublines of a newly established Burkitt's lymphoma cell line

Abstract

Cytogenetic observations were made in a newly established Burkitt's lymphoma cell line (B46M) and its 10 cloned sublines. The parental cell line had a fairly sharp mode of 46 chromosomes with a normal male karyotype, except for the presence of two marker chromosomes (a B‐group chromosome with an elongated short arm and a G‐group chromosome with a partially deleted long arm). In spite of the high karyologic homogeneity (70%) in the parental cell, population, it was found that only 2 clones contained the same chromosome complement as that of the parental cells. Five clones had 1 or 2 additional modes at 45 or 47, besides 46, in which most cells maintained the parental karyotype. In these cases, there was a preferential loss and addition of G and C‐X‐group chromosomes, respectively. Each of the remaining 3 clones showed a common chromosomal abnormality in all the cells examined—a partial monosomy for the long arm of E18, an absence of the Y‐chromosome, and a possible isochromosome of one of D13–15. The evidence for the production of both γ and μ heavy chains and χ light chain in all the clones, as well as in the parental cell line, suggests that the genes controlling the immunoglobulin synthesis were not located on the parts of the 3 chromosomes described. The mechanism by which the variant clones were developed from the parental cells was discussed, with some remarks on the possible usefulness of the system employed in the present study in obtaining mutant clones necessary for studying human genetics in vitro.