Dose-response relationships for chromosome aberrations in peripheral blood lymphocytes after whole- and partial-body irradiations. I. Effects immediately after irradiation.

Dose-response relationships were established for yield of dicentrics and for a fraction of damaged metaphases in lymphocytes after gamma-irradiation of rabbits' whole blood in vitro. These relationships were based on the scoring of cells only in their first post-stimulation division and they served as a reference system for comparison with results of 60Co gamma-irradiation in vivo, either of the whole or of predetermined parts of an animal's body. There was a statistically acceptable agreement between dose-response data established for dicentric yield after whole-body irradiation in vivo and the reference dose-response curve derived from exposure of rabbit's blood in vitro. For partial-body (1/2) irradiations there was a satisfactory agreement between the dose-response curves in vitro for dicentric yield and fraction of metaphases damaged on the one hand and the response in vivo when the latter was related to mean doses to circulating blood. However, there was a drastic disagreement with the dose responses in vitro when measured cytogenetic quantities were plotted versus mean doses to body mass. When the latter were substituted for by comparable doses to circulating blood the in vivo-in vitro agreement was acceptable after irradiation of 'cerebral' 1/2 mass and very much improved for the 'caudal' 1/2 exposures. Therefore, it is concluded that, after partial-body irradiations, the dicentric yield or fraction of damaged metaphases in lymphocytes sampled immediately after exposure reflect mean dose to circulating blood irrespective of whether or not this dose coincides with mean dose to body mass.