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Abstract: Interleukin-2 (IL-2) is able to generate nonspecific cytotoxic effectors from hematopoietic precursors. We evaluated the feasibility and efficacy of chronic myeloid leukemia (CML) treatment with autologous hematopoietic stem cell transplantation (HSCT) using grafts cultured in IL-2 followed by immunotherapy with IL-2, granulocyte-macrophage colony-stimulating factor (GM-CSF), and interferon (IFN)-α. Eight patients with CML were enrolled: five in an accelerated phase and three in a chronic phase. They received peripheral blood stem cells (PBSC) or bone marrow (BM) cultured in a medium containing IL-2 for 24 h. A median of 1.29 × 106 CD34+ cells/kg were infused after conditioning with busulfan (12–16 mg/kg) in PBSC recipients. BM was infused without prior myeloablative therapy. The engraftment occurred with a median of 15 d. Engraftment failure developed in one patient. The transplantation was followed by a 1-mo regimen of IL-2 (0.5 × 106 IU/m2 daily) and GM-CSF, and 6 mo of IFN-α. One complete and one transient minor cytogenetic remission were observed. At 24 mo after transplantation, two patients had died of progressive disease and one of infection. Five patients had stable disease in the chronic phase. Autologous transplantation using IL-2-activated graft is feasible and the subsequent IL-2, GM-CSF, and IFN-α administration has acceptable toxicity. However, no benefits in comparison with conventional autologous transplantation for CML were identified in our study.

The induction of sister chromatid exchanges (SCEs) inVicia fabaroot-tip cells after short-term (2 h) and long-term (24 h) treatments with alkylating agents (N-methyl-N-nitrosourea, ethyl methanesulphonate) and maleic hydrazide was studied. The primary roots were treated with mutagens before or after 5-bromodeoxyuridine (BrdU) incorporation into DNA and the influence of mutagen application on SCE induction in the cells with non- and BrdU-substituted chromosomal DNA. On the contrary, application of maleic hydrazide after the incorporation of BrdU into DNA strongly increased the rate of SCEs. The lowest limit concentrations of mutagens capable of significantly increasing SCE frequency in the cells with non-substituted DNA after the long-term treatment were estimated.

Genomic instability of protoplast-derived tobacco plants was studied by means of phenotypic evaluation, karyological analysis, and Southern blot experiments. Of the total number of 91 regenerants belonging to 35 different protoclones 57 plants displayed various morphological and/or functional aberrations, some of them being inherited into the progeny. A karyological study of 20 randomly chosen plants revealed 15 tetraploid and 5 diploid chromosome sets. A Southern blot hybridization analysis of three regenerants displayed some DNA polymorphism (RFLP) and thus confirmed that in such plants alterations in the genome structure could be found and that genotypes of protoplast-derived plants frequently differ from the parental genotype.

Primary roots ofVicia fabawere grown for 24 h in the presence of tritiated thymidine (1.85–18.5 kBq ml−1) and then irradiated with a dose of 1.5 Gy of60Co-gamma- rays. The aim of these experiments was to determine whether low-level endogenous beta-irradiation from incorporated radioactive thymidine could influence the frequencies of sister chromatid exchanges (SCEs) and the numbers of micronuclei induced by subsequent external irradiation with high doses of gamma-rays. The results demonstrated that the pretreatment with3H-dTh had no significant effect on the frequencies of SCEs in gamma-irradiated root tip cells ofVicia faba. In contrast to SCEs, the yields of micronuclei in the3H-dTh pretreated cells were altogether less than the yield induced by gamma-rays alone (protective effects).

Germinated seeds ofVicia fabawere continuously irradiated at low dose rate of gamma rays (0.05 Gy h-1) up to a total accumulated dose of 2 Gy. The FPG (fluorescence plus Giemsa) technique of differential chromatid staining was used to monitor the frequency of sister chromatid exchanges (SCEs) in irradiated root tip meristem cells. The results of the experiments have demonstrated that SCE frequency is raised by continuous gamma irradiation only in plant cells containing BrdU in the chromosomal DNA. No effect concerning SCE formation was recorded at continuous irradiation of meristematic cells of Vicia faba with native, i. e. BrdU-nonsubstituted, DNA. In contrast to SCEs, a significant increase was found in the yield of chromosomal aberrations in all variants of irradiation.

Pretreatment ofVicia fabaroot tip cells with low doses of60Co γ-radiation can reduce the yield of micronuclei induced by a subsequent high dose of γ-radiation (1.5 Gy). This adaptation to γ-radiation possesses the following characteristics: (1) this phenomenon can be induced by an optimal range of low doses of γ-radiation applied acutely or fractionally; (2) the expression of this response seems to be transitory and depends on the time interval between adapting and challenging doses of γ-radiation.