Leukocyte Response to Exercise in Atomic Bomb Survivors

Two hundred and fifty-four male and female subjects of a population followed for delayed effects of atomic bomb (A-bomb) radiation were examined for changes in circulating leukocytes before and after moderate exercise. The exercise was an augmented two-step test used routinely for cardiac evaluation. None had postexercise ischemic electrocardiogram changes. An immediate increase in mean pulse rate (70.2-120.6/minute) was obtained. The group showed statistically significant increased means for total white blood cell (WBC) count (by 33%), mature granulocytes (20%) and lymphocytes (60%). Comparison of pre- and postexercise counts showed no relation to A-bomb radiation dose. For granulocytes incremental change correlated with initial granulocyte and lymphocyte counts and with age, but not with change in pulse or radiation dose. Findings for total WBC and lymphocyte counts are given. The observation that the circulating granulocyte pool is similarly responsive to exercise stimulation in A-bomb survivors and controls still does not rule out possible radiation-induced changes in hematopoietic capability. Changes in lymphocytes, while striking, are difficult to interpret because of their extramedullary sources.