Bystander effect in human lymphocytes incubated with irradiated mitochondrial DNA deficient yeast cells

Abstract

The comparison of strength of bystander effect induction in human lymphocytes by rho 0 (complete loss of mitochondrial DNA) and rho + (with fully functional mtDNA) strains of Saccharomyces cerevisiae was carried out. The cultures of human peripheral blood were experimentally contaminated with nonirradiated or X-ray irradiated yeast cells (haploid rho 0 and rho + strains of S. cerevisiae ). The doses of irradiation were 1 and 10 Gy. Well spread human metaphases were scored for chromosomal aberrations (CA). It was found that nonirradiated yeast cells (no matter rho 0 or rho + ) had no effect on lymphocytes chromosomal stability. Statistically significant increased level of CA was observed in lymphocytes incubated with irradiated rho + yeast cells. The increasing of the CA was dose independent. However, after cocultivation with irradiated rho 0 cells the bystander effect was revealed for dose 10 Gy only and his manifestation was mild in comparison with rho + data. Thus, our findings suggest that strength of bystander effect depends on existence of mitochondrial DNA and normally functioning mitochondria.