Radiation sensitivity and chromosomal changes in human leukemic T-cell lines.

Abstract

Radiosensitive and resistant cell lines were studied with regard to radiation survival and chromosomal changes. A radioresistant cell clone (CCRF-HSB2-M) was spontaneously separated from a radiosensitive human T-cell line (CCRF-HSB2) which was originated from the peripheral blood of the patient with an acute lymphoblastic leukemia (ALL). Cell growth and dose-survival curves after X-irradiation indicated that HSB2-M cells were as resistant as normal cells, though the frequency of chromosomal aberrations in irradiated HSB2-M cells was slightly higher than that in irradiated normal cells. Higher frequencies of chromatid and chromosome deletions (breaks) were observed in irradiated HSB2 cells, whereas those of deletions in HSB2-M and normal cells showed a relatively low frequency and the chromosomal aberrations in these two cell lines decreased with time. The karyotype of radiosensitive HSB2 cells was XY, 46, t(1;7)(p32;q32). The radioresistant mutant clone (HSB2-M) gained some other changes in addition to the original translocation; 47, XY, t(1;7)(p32;q32), +t(6;6)(p11;q13), t(12;16)(q24;q11), -16p, +22. The acquirement of radioresistant character in HSB2-M cells could be closely related to the additional chromosomal changes (+iso6q and +22). The emergence of a radioresistant clone from a radiosensitive cell line is discussed in relation to human leukemia.