Nuclear lysate sedimentation measurements of peripheral blood lymphocytes from radiotherapy patients

When isolated nuclei of human lymphocytes are challenged with 2 M NaCl a histone-free-DNA-protein (HF-DNA) complex is released. In a linear sucrose gradient (pH 8.0) the sedimentation distance of HF-DNA is reduced when immediately isolated from cells irradiated in vitro. At low doses, if irradiated cells are incubated at 37 degrees C the sedimentation behaviour approaches that of unirradiated cells (i.e. repair). In the present study such repair was usually complete within 1 h. The radiation damage to lymphocytes from a healthy donor group and three patient groups consisting of new patients (before radiotherapy), well patients (2 to 6 years post-radiotherapy) and patients with complications attributed to radiotherapy was similar. The lymphocytes from most healthy donors and new patients demonstrated complete repair of radiation damage following an incubation of 1 h at 37 degrees C. However, 2/29 (6.9 per cent) healthy donors and 2/25 (8 per cent) new patients demonstrated poor repair. Of those patients now attending with 'bowel complications' attributed to radiotherapy 7/16 (44 per cent) demonstrated poor repair. In contrast, all those (11/11) described as 'well and complication-free' showed good repair.