The Medical Research Center Brookhaven National Laboratory AQ LQ22 Upton, L. L, New York Early and Late Cytologic Effects of Whole Body Irradiation on Human Marrow By T. M. Fuiepner, Goutp A. ANDREWs, EuGENE P. CRONKITE AND Victor P. Bonp HE HEMATOLOGIC manifestations of whole body irradiation in man have been studied extensively.!}? These studies have been based on ex- posures in nuclear warfare,'* on accidents in laboratories or fallout field,?° and on large volume radiation therapy. They have been reviewed in detail recently.!8 Serial examinations of blood cell levels (neutrophilic granulo- cytes, lymphocytes, platelets and reticulocytes) have been found to be an indispensable aid in the clinical assessment of the exposed individual. In most of the surviving persons, blood cell counts returned to approximately preirradiation levels within a few months, although someslight but statistically significant changes are seen to persist for years when adequate control data are available. Furthermore, despite apparent recovery, chromosomal ab- normalities persist in hemopoietic cells, as demonstrated by blood cell cultures or bone marrow examination,"*suggesting a persisting latent injury. In most of these studies, bone marrow examinations have not been per- formed or have not been reported in detail. Their value in the evaluation of the exposed person has not been clearly established and it has even been suggested that they are dangerous because of the possibility of introducing infection. Little is known about bone marrow changes in man after whole body ir- radiation as a function of time and dose. However, extensive studies in ex- perimental animals have shown characteristic cytologic and histologic consequences during the first hours and days after exposure.'™*! Since the marrow is one of the most radiosensitive organs of the body, serial examinations after radiation exposure should provide valuable additional information both for clinical management and for a better understanding of the pathogenesis of marrow failure secondary to ionizing radiation. Samples can be obtained with ease and repeatedly, and the danger of infections is small. (They apparently have not been reported?*). It is the purpose of this paper to describe some of the cytologic manifesta- tions of radiation injury in marrow smears of eight men “early” (during the first 2-3 weeks) and “late” (3.5 years) after accidental exposure to mixed neutron-gammairradiation. From these results, some guidelines can be derived for a diagnostically more meaningful evaluation of marrow smears under such circumstances. Details about the accident, the general hematologic findings From the Medical Research Center, Brookhaven Nationa? Laboratory, Upton, N. Y., and Medical Division, Oak Ridge Institute of Nuclear Studies, Oak Ridge, Tenn. Research supported by the U. S. Atomic Energy Commission and presented in part at the IX Congress of the International Society of Hematology, Mexico, September 1962. Submitted July 25, 1963; accepted for publication Sept. 17, 1963. 47) REPOSITORY BN2. RECORDS COLLECTION ZARSHALL BOX No. MEDIAL DEPT, FOLDER ~2276 - 698 Bioop, Vou. 23, No. 4 (Apri), 1964 (SLANOS FUBLICATIONS pee ey ae vUL 2274i a

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