[An individual variability of the adaptive response to irradiation in human cells. Approach to its determination]

On human blood lymphoxytes with micronuclei (MN) assay and cytokinetic cytochalasin block and analysis of chromosome aberrations the change of cell population composition, adaptive response (AR) and phenomenon of enhanced radiosensitivity after low dose (5 cGy) and challenge doses (1.0 Gy) have been studied. Irradiation have been carried out in G1 and G2 phases of cell cycle (24 h and 48 h after PHA stimulation). Fixation of cells have been conducted after 50 h (2 h after demecolcin adding) and 72 h (24 h after cytochalasin adding) chromosome and MN assay. Evaluation criteria were the frequency of binucleated cells with MN on 1000 binucleated cells and the frequency of cells with chromatid aberration on 100 metaphases. It was shown that cell population constitution change, AR occurring depended on the individual peculiarity. The evaluation of AR presence by the indexes of bimucleated cells with MN frequency and cells with chromatid aberrations don't coincide (coincidence is observed in 3 cases from 15). It is supposed that in G2 phase after irradiation in challenge dose the MN assay and metaphase analysis can register different cells (24 h and 2 h after mitotic block). The cell population constitution change can probably influence on the AR evaluation but in isn't the AR mechanism. The main mechanism of AR forming * the protection from the damages by different ways. AR depends on many factors, individual peculiarities observes by the use of definite evaluation criteria, in individuals with definite genetic constitution. Perhaps these considerations permit to discuss the problem of AR universality.