y \f^z: 7'^J^PO^-7/x MOOC - 912 ) r^N UNITED STATES ATOMIC ENERGY COMMISSION EFFECTS OF RADIATION EXPOSURE ON THE CELLS OF THE PERIPHERAL BLOOD by Edna K. Marks Argonne National Laboratory This document consists of 3 pages. Date of Manuscript: March 1947 Date Declassified: March 10, 1947 This document is issued for official use. Its issuance does not constitute authority to declassify copies or versions of the same or similar content and title and by the same author(s) Technical Information Division, Oak Ridge Directed Operations Oak Ridge, Tennessee DOC U ME. NTS npPT r \^ us OEPOSiTORY < EFFECTS OF RADIATION EXPOSURE ON THE CELLS OF THE PERIPHERAL BLOOD By Edna K. Marks INTRODUCTION Since more radioactive isotopes as phosphorus, iodine, etc. are being made available to the medical profession for research and therapy, it seems pertinent that the medical technologist, especially those engaged in hematological work, be kept abreast with recent developments in this field. The laboratories operated by the Atomic Energy Commission and the regular university and industrial laboratories now concerned with problems related to radiations increases by thousands the number of individuals exposed to these various radiations, and many technicians are or will shortly be concerned with the medical or research aspects thereof. It is important, therefore, that the technicians should be familiar with those changes which may occur in the cells of the peripheral blood following exposure to externally originat- ing radiations or radioactive isotopes. In 1903 Heineke described the damage to the hemopoietic organs of animals following X irradiation. Most of the morphological damages described were those of the cells found in the blood forming tissue. Since that time the effects of roentgen rays, gamma rays, fast neutrons, and radioactive substances on the blood and the blood-forming tissues have been studied extensively. These histological changes ob- served in the blood-forming tissue are essentially paralleled in the peripheral blood of experimental animals and patients undergoing X-ray therapy or therapy with radioactive materials. ERYTHROCYTES A reduction in the erythrocyte values per cu mm may be expected following acute and chronic total body irradiation. The anemia which occurs following chronic total body irradiation in animals may be normocytic, hyperchromic, or macrocytic, depending upon the size of the accumulated dose and the sensitivity of the species of animal used. A macrocytic anemia with marked anisocytosis frequently develops in patients after the administration of total body X irradiation, after radioactive phosphorus therapy for polycythemia, and in experimental animals after the administration of strontium and other radioactive isotopes. After semi-lethal acute total body X irradiation in animals, and to a lesser extent after doses below this value, nucleated erythrocytes appear in the peripheral blood in increased num- bers. The maximum number is seen between the tenth to the twenty-fifth day after radiation exposure, which represents the period of maximum anemia in the peripheral blood and the maximum regeneration in the bone marrow. The degree of polychromatophilia and anisocytosis depends largely on the type and chronicity of the anemia. Very occasionally, pyknotic degenerative changes are seen in the nucleated red cells. Howell-Jolly bodies are rarely found. Occasionaiiy a few stippled red cells are seen during the stage of anemia. The total number of reticulated erythrocytes is reduced following radiation exposure, depending upon the size of the dose. Careful examination of the reticulocytes stained with brilliant cresyl blue, how- ever, fail to show any change in the morphological character of the reticulum following X irradiation or exposure to radioactive isotopes. PLATELETS Degenerative morphological alterations in the thrombocytes are found in the peripheral blood of animals following semi-lethal or even higher doses of total body X irradiation or exposure to radioactive MDDC - 912 (1 2 ] MDDC - 912 isotopes. Concomitant with the reduction in platelet values, giant thrombocytes are frequently found. These thrombocytes are occasionally larger than normocytes. The hyalomere is extremely abundant and the granules in the chromomere are unusually prominant and large. Except for the size and the clear distinctive colorful granular degeneration, no further morphological alterations are detected. On very rare occasions a megakaryocyte is found in the peripheral blood following exposure to semi- lethal or lethal total body X irradiation. LEUKOCYTES That radiation exposure produces a marked decrease in the total number of leukocytes, depending on the size of the dose, is well known. In acute exposure there is an initial, transient leukocytosis which precedes the rapid decline in the leukocyte values. The most sensitive cellular constituent of the peripheral blood appears to be the lymphocyte and the reduction in its values closely parallels that of the total number of leukocytes per cu mm. The morphological changes in the lymphocytes of the peripheral blood after acute total body X irradiation agree essentially with those seen upon histological examination of the lymphatic tissue in sacrificed animals. With semi-lethal doses, and to a lesser extent after doses below this value, mitosis ceases within an hour and destruction and phagocytosis of lymphatic cells, mainly small and medium lymphocytes, proceeds. The same general kind of destructive changes seen histologically is apparent in the peripheral blood of animals and humans. With increasing amounts of radiation exposure, the number of lympho- cytes in the circulating blood with abnormal morphological characteristics increases. A clumping of nuclear chromatin may be seen early. As it becomes more pronounced, pale bluish opaque areas are encountered. In addition, lymphocytes are seen with rounded chromatin masses seemingly free within the nuclear border or free within the cell, with an apparent disappearance of the nuclear membrane. "Blast-like" cells are occasionally seen with nuclei which appear to be dissolving. Concomitant with the point of maximum lymphocyte reduction, many lymphocytes become basophilic and nucleoli are often prominant. These latter cells are indistinguishable from "blast" forms. Other lymphocytes appear to have split nuclei and nuclei with considerable fragmentation. With semi-lethal doses of acute total body irradiation in animals these destructive changes are more pronounced. Remnants of nuclear fragments without nuclear outline appear which cannot be distinguished as belonging to either the myeloid or lymphoid series. Many lymphocytes are bilobed, still others become difficult to distinguish from monocytes. During the peak of lymphocyte destruction, phagocytic monocytes with engulfed nuclear debris are found in the peripheral blood smears. Often these cells are bilobed with chromatin masses in one part of the nucleus while the other portion r' the nucleus appears normal. This phagocytic prop- erty of certain cells was described by Heineke in 1905. During the phase of regeneration in the bone marrow the heterophils in the circulating blood of rabbits show a shift to the left following acute total body X irradiation. During the phase of rapid reduc- tion of heterophil values, degenerating granulocytes are seen in the peripheral blood. These degener- ating leukocytes show nuclear deformity and disintegration to the extent that it is impossible to deter- mine at which stage of maturity the cells are damaj; i. The nuclear membrane has been destroyed, and in most instances bluish non-specific granules of uneven contour fill the entire cell covering the nucleus and cytoplasm to such an extent that it is impossible to identify the cell other than to say it is a damaged leucocyte. Other bizarre forms are also seen which are difficult to describe. The cytoplasm of the heterophil may undergo degeneration following irradiation. Occasionally it contains vacuoles and has a mottled appearance. In some instances the granules of the hetorophils appear to be degenerating since cells are found in which the. few granules which remained are hugging the nuclear membrane, while the remainder of the cytoplasm remains clear. Another type of degenerative cell seen after semi-lethal doses of total body irradiation in rabbits is one which resembles a basket cell, but differs from it in having one or two distinct chromatin masses which are deep blue against a network of destroyed peri- chromatin and cytoplasmic disintegration. Eosinophilic degeneration is occasionally seen, especially in the peripheral blood smears of the dog, following semi-lethal and lethal doses of total body irradiation. This degeneration is characterized by MDDC - 912 [3 irregularity in the granules both with regard to size and shape. Vacuoles in the cells become more abundant. Similar changes to those described above are found in patients after total body X irradiation with 150 roentgen units administered in divided doses over periods of approximately 30 days. The most constant morphological abnormality in the peripheral blood of these patients is the appearance of the degenerating cell described previously. This cell could easily be mistaken for a polymorphonuclear basophil by an inexperienced worker. It appears as early as 3 days after the first exposure and is present in almost every peripheral blood smear throughout treatment and may still be present 2j months after treatment ceases. Giant polymorphonuclear neutrophils are frequently seen which appear swollen and contain multilobed nuclei which are spread over the cytoplasm like globules with an ex- tremely fine filament branching off into eight or more lobes. Degenerating lymphyocytes are found which show the characteristic massing of nuclear chromatin and general disintegration. Very occa- sionally, such cells contain round and rod-shaped bodies within the cytoplasm. Although they have the appearance of lymphocytes, it is possible that they are atypical and abnormal monocytes with ingested material which has been phagocytized. Radioactive isotopes as plutonium, strontium and phosphorus give essentially the same results. As early as four days after treatment, the peripheral blood smears of these patients may contain monocytes with nuclear deformities which show disintegration, lympho- cytes with split or bilobed nuclei, and other morphological alterations previously described. Studies on the supravital staining (Janus green and neutral red) of leukocytes were made on the blood of humans and rabbits which had received external or internal irradiation. Mitochondrial changes are variable. Neutral red granules appear in the lymphocytes concomitant with the increase in monocytes. SUMMARY AND CONCLUSIONS Profound radiation effects are detectable by the observation of the number and morphological changes of the cells in the peripheral blood. The most sensitive cell appears to be the lymphocyte both in terms of reduction per cu mm and morphological changes. The platelets are reduced in number and an anemia usually occurs. The severity of these changes is dependant upon the size of the accumulated dose. This report is based on work done under the auspices of The Manhattan District at the Metallurgical Laboratory, University of Chicago. UNIVERSITY OF FLORIDA lllll illlill 3 1262 08907 9890 iO