EFFECT OF EX-VIVO HYPERTHERMIA ON RADIATION-INDUCED MICRONUCLEI IN LYMPHOCYTES OF CANCER-PATIENTS BEFORE AND DURING RADIOTHERAPY

To investigate the effect of ex vivo hyperthermia (HT) and Cs-137-irra diation on micronucleus (MN) production in cytokinesis-blocked lymphoc ytes, we obtained the peripheral blood samples from the same cancer pa tients (n = 6) before and during fractionated partial-body radiotherap y (xRT). The whole blood cultures were heated at 43.5 degrees C for 60 min, followed by Cs-137 irradiation (0-4 Gy). The control cultures fr om the same patients were incubated at 37 degrees C after being expose d to radiation. The lymphocytes were then stimulated with PHA. Cytocha lasin B was applied at 44 h, and lymphocytes were harvested at 72 h. M N frequency was determined on Giemsa-stained slides. We found that in patients before xRT, HT (43.5 degrees C) significantly increased the M N yield (mean +/- SEM) in unirradiated lymphocytes from 15.6 +/- 2.8 ( 37 degrees C) to 39.7 +/- 10.9. Further, in patients either before or during xRT, when the lymphocytes were treated with HT (43.5 degrees C) and combined with ex vivo irradiation, the MN yield (Y) could be esti mated by a linear equation Y = C + alpha D. Our findings indicate that as measured by the MN production in cytokinesis-blocked lymphocytes, HT alone at 43.5 degrees C induced DNA damage. Moreover, it enhanced t he radiation-induced cytogenetic damage. Therefore, the application of HT may impair the T-cell function in cancer patients who are receivin g radiotherapy. (C) 1998 Elsevier Science B.V. All rights reserved.