State of Bone Marrow Hematopoiesis in Chronic Radiation Disease Patients, Irradiated with Different Dose Rates

Purpose: to study the features of the state of the bone marrow according to cytological and histological studies at different periods of the course of CRD, caused by exposure to different dose rates, which developed as a result of professional prolonged exposure in a cohort of former employees of a radiation hazardous enterprise who underwent inpatient examination at the clinic of the A.I. Burnazyan Federal Medical and Biomedical Center in the period up to 1995.

Material and methods: the study of the results of cytological and histological studies of the bone marrow was carried out in former workers of the Mayak Production Association who were exposed to long-term industrial exposure with a dose rate of 0.008−0.07 Gy / day (15 people), 0.003−0.007 Gy / day (12 people) and less than 0.001 Gy/day (25 people), during periods of formation, outcomes, immediate and long-term consequences of CRS. At the stage of studying the results of histological examination of the bone marrow, 54 more patients with CRS were added to the third group, irradiated with a dose rate of less than 0.001 Gy / day.

Statistical processing of the material was carried out using the IBM SPSS Statistics software package.23 using the Kruskal‒Wallis test and the Mann‒Whitney U-test for independent samples. The results obtained were considered statistically significant at p < 0.05.

Results: At a dose rate of 0.008−0.07 Gy / day during the formation period, the myelogram revealed narrowing of the granulocyte and expansion of the red germs, acceleration of maturation of granulocytes with a normal erythrocyte maturation index and leuko-erythroblast ratio. In peripheral blood – agranulocytosis. In the period of outcomes and immediate consequences − narrowing of the granulocytic, expansion of erythrocyte germs, acceleration of maturation of neutrophils with other myelogram parameters within normal limits. In the blood − agranulocytosis, anemic syndrome. In the long term, in the case of restoration of hematopoietic function, narrowing of the granulocytic germ with other myelogram parameters within the reference values. However, with a similar course of CRS in 60 % of patients in periods of outcomes and long-term consequences, the development of myelodysplastic syndrome with transformation into acute leukemia or aplastic anemia is possible.

At an irradiation dose rate of 0.003−0.007 Gy / day in the period of CRD formation, the myelogram revealed an expansion of the granulocytic germ, with other indicators within the normal range. In the period of outcomes and immediate consequences, an acceleration of maturation of granulocytes and an increase in the leuko-erythroblastic ratio were found. In the long term, a narrowing of the granulocytic and expansion of the erythrocyte sprouts, a slight acceleration of the maturation of granulocytes were found. Hystological examination: polymorphocellular bone marrow – in 11 out of 25 patients, hypoplasia – in 9 out of 25, signs of hyperplasia – in 5 out of 25. In the long term, 2 patients from this group developed oncohematological diseases.

At an irradiation power of less than 0.001 Gy / day, during all periods of CRD, normal values of granulocytic and erythrocyte sprouts were noted in the myelograms of patients. In the period of CRD formation, the normal size of the granulocytic germ was achieved due to the accelerated maturation of neutrophils. The leuko-erythroblastic ratio in the period of long-term consequences was significantly higher than the norm (5.29 and 4.5, respectively). Hystological examination: 32 out of 64 patients had polymorphocellular bone marrow, 22 out of 64 had hypoplastic bone marrow, 7 out of 64 had bone marrow hyperplasia.

Conclusion: regular changes in hematopoietic tissue and peripheral blood in CRD can serve as diagnostic criteria, based on which it is possible to assume the dose rate of radiation to which the patient was exposed, and also on their basis, it is possible to predict the outcome and long-term consequences of CRD that developed as a result of this exposure.