Total-body irradiation and human chromosomes. V. Additional evidence of a transferable substance in the plasma of irradiated persons to induce chromosomal breakages.

A substance (or substances) produced or activated by total-body irradiation in man and capable of affecting the chromosomes for an extended time has been postulated. Leukocytes from normal persons were cultured with autologous plasma, homologous plasma or serum from patients irradiated 10.5 years previously. Thirty (5.5%) chromosomal breaks were found in the 550 metaphases from the control cultures, 152 (13%) in the 1,175 metaphases from the irradiated plasma cultures and 130 (12%) in the 1,100 metaphases from the irradiated serum cultures. This finding confirms and extends our previous observation that plasma from total-body irradiated persons is capable of inducing chromosomal breakage in normal leukocytes even 10.5 years after the irradiation.