A high incidence of leukemia and cancer has been observed among heavily exposed atomic bomb survivors in Hiroshima and Nagasaki. They have also been found to have a moderate to high percentage of chromosome aberrations in T lymphocytes and bone marrow cells. Because of technical difficulties in obtaining mitosis of B lymphocytes alone, the presence of chromosome abnormalities has not been demonstrated in these lymphocytes. In this study we have established a new method for culturing individual B lymphocytes sensitive to EB-virus as a colony on soft agar and transferring them to liquid culture for further cell growth. It was found that B lymphocytes from heavily exposed survivors (cases Y. M. and M. S.) still have 50 and 12.5 percent of chromosome aberrations even 30 years after the atomic bomb exposure. No abnormal cells with chromosome aberrations were detected in two other cases as in the control group. Cases Y. M. and M. S. had 38 and 21.5% of T lymphocyte aberrations and 39 and 28.6% of chromosome aberrations in bone marrow cells respectively.
The method used in this study and the evidence of chromosome aberrations in B lymphocyte for a long period after radiation exposure would be useful in elucidating the process of acute lymphocytic leukemia (B lymphocyte), B cell lymphoma and multiple myeloma.
