SCE in Bloom syndrome B and T lymphocytes

Genotoxicity and sister chromatid exchange in patients with myelodysplastic disorders

In this study, we aimed to evaluate genotoxicity by sister chromatid exchange frequency in the peripheral lymphocytes of patients with myelodysplastic syndrome (MDS). The study population consisted of 16 patients (females/males:6/10; mean age: 61.68 +/- 13.08 years) diagnosed with "refractory anemia" according to FAB classification. The results were compared with an age- and sex-matched control group. The sister chromatid exchange frequency in the study group was found to be significantly higher than the control group (8.3 +/- 11 vs. 6.83 +/- 1.07, P=0.0046). We suggest that increased DNA damage, which is revealed by the increased sister chromatid exchange in the present study may play a role in the etiopathogenesis of MDS.

Sister chromatid exchange in immature haemopoietic cells, T- and B-lymphocytes

T-lymphocytes, B-lymphocytes, and cells derived from human haemopoietic progenitor cells were analysed for their sister chromatid exchange (SCE) rate. T- and B-lymphocytes were separated and stimulated with phytohaemagglutinin (PHA) and Epstein Barr (EB) virus respectively, while the progenitor cells were cultured in the mixed colony assay. B-lymphocytes had a significantly lower SCE rate than either the T-lymphocytes or cells derived from progenitor cells.

Cytogenetic study in a mentally retarded child with Bloom syndrome and acute lymphoblastic leukemia

Bloom syndrome (BS) was diagnosed in a 7-year-old boy during hospitalization for acute lymphoblastic leukemia (ALL). The patient had most of the signs of BS along with some atypical manifestations: absence of telangiectases, obesity, and moderate mental retardation. Results of the cytogenetic studies were fully consistent with the diagnosis of BS: the occurrence of quadriradial figures and a very high incidence of sister-chromatid exchanges (SCE). This child's ALL was of non-B, non-T type with the presence, at the time of diagnosis, of a marrow clone including two markers. A Yq - chromosome was detected in about 10% of PHA-stimulated lymphocytes but neither in bone marrow cells nor in skin fibroblasts. This case is the fifth instance of ALL out of 104 registered cases of BS.

Sister chromatid exchange levels and cell cycle time in human bone marrow cells and lymphocytes

The frequency of sister chromatid exchange (SCE) and the cell-cycle-specific pattern of mitoses were analyzed at the same time in normal bone marrow cells and lymphocytes of six healthy donors. The SCE frequency was found to be significantly higher in lymphocytes. The cell-cycle-specific pattern revealed significantly shorter cell cycle times for normal bone marrow cells as compared with those of phytohemagglutinin (PHA) stimulated lymphocytes. Chromosomes of bone marrow metaphases displayed a more contracted morphology.