Cultures of human leukemic cells derived from the peripheral blood buffy coats of pediatric patients in whom the presenting lymphoma had progressed to acute lymphoblastic leukemia were studied with respect to their l-cystine requirements in both the diploid and, following serial passage in intact newborn Syrian hamsters, the heteroploid state. With one exception, all of these cultures exhibited an absolute requirement for l-cystine which was independent of state of ploidy and cell population density. The classical methionine-cystine pathway appears to be defective or lacking in these cells, and unlike other kinds of cells, the development of heteroploidy did not effectively de-repress the metabolic pathways concerned with the biosynthesis of cystine. The one exception was the CCRF-SB culture which utilized l-cystathionine for growth, in contrast to the inability of the other cultures so examined to utilize this precursor of l-cystine; including the CCRF-H-SB-2 cells which were derived directly in intact newborn Syrian hamsters by implantation of the same peripheral blood buffy coat specimen from which the CCRF-SB cells were isolated in culture. Unlike the CCRF-H-SB-2 cells (and the others considered herein), the CCRF-SB cells do not implant in intact newborn Syrian hamsters. Whether the difference in their ability to utilize l-cystathionine relates to the fundamental biological distinction suggested by the differences in their heterotransplantability, or merely reflects the divergent development of different stem lines of leukemic cells is unclear at the present time. © 1969.
