Transformation and Repair Replication in Lymphocytes from Ataxia Telangiectasia

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Abstract
Peripheral blood leukocytes (PBL) isolated from 5 patients with ataxia telangiectasia (AT) proved more difficult to transform following addition of exogenous Epstein-Barr virus than PBL isolated from AT heterozygotes or normal adults. PBL isolated from one AT patient transformed within the range expected for normal PBL. Once established in culture, the resulting lymphoblastoid cell lines (LCL) were immortal and, though they grew slower than normal control LCL, provided useful material for studying cellular phenotypes associated with AT lymphoid cell lines. All the resulting LCL established from ataxia were more sensitive to X-irradiation than were LCL established from controls as measured by colony formation in microtiter plates. X-ray-induced inhibition of semiconservative DNA synthesis in ataxia LCL was less than that seen in normal LCL. These results are in agreement with those obtained using cultured AT fibroblasts, indicating that in vitro transformation by exogenously added Epstein-Barr virus does not alter the phenotype of the ataxia cell as measured by these 2 parameters. No deficiency in X-ray-induced excision repair of DNA was demonstrable in LCL established from 4 AT patients. Nor was there a deficiency in AT LCL host cell reactivation of herpes simplex virus X-irradiated under anoxic conditions. A defect in ataxia lymphoblasts other than repair enzyme(s) per se is implicated, one possibly associated with chromosomal structure, function or modification.