Hematological effects in dogs after sequential irradiation of the upper and lower part of the body with single myeloablative doses.
The compensating mechanisms determining the tolerance of the hemopoietic system to sequential hemibody irradiation (HBI) with large single doses, the regeneration of the irradiated bone marrow and the long-term effects of such treatment were studied in dogs. The main emphasis was laid on the determination of the granulocyte/macrophage progenitor cells (GM-CFC) in the bone marrow and blood. The general pattern of events in the GM-CFC compartment after each exposure was similar. Irradiation with a dose of 11.7 Gy of the upper body (UBI), that involved the abrogation of approximately 70% of the total active marrow, was followed by an immediate increase in the proliferation and differentiation of GM-CFC in the protected bone marrow. Repopulation of the GM-CFC in the irradiated sites most probably due to seeding of hemopoietic cells from the protected marrow already became evident at day 7 after UBI. At day 56 after UBI, when the irradiation of the lower body (LBI) was performed, the GM-CFC had recovered to between 30 and 40% of their pre-treatment values. Despite this incomplete regeneration, the GM-CFC compartment responded to LBI in a similar way as the GM-CFC had in the protected (normal) marrow after UBI, i.e. by an increased proliferation for at least 21 days. Already at day 7, the bone marrow of the iliac crest that had been exposed to LBI showed a considerable number of GM-CFC. Within no more than 370 days all the bone marrow sites irradiated during either the first or the second treatment had regained their normal GM-CFC values.
Nothdurft
W
W
Institute of Occupational and Social Medicine, University of Ulm, F.R.G.
Baltschukat
K
K
Fliedner
T M
TM
D000818:Animals; D001792:Blood Platelets / Q000528:radiation effects; D001853:Bone Marrow / Q000473:pathology / Q000528:radiation effects*; D002453:Cell Cycle / Q000528:radiation effects; D004285:Dogs; D004307:Dose-Response Relationship, Radiation; D006098:Granulocytes / Q000378:metabolism / Q000528:radiation effects; D008214:Lymphocytes / Q000528:radiation effects; D008264:Macrophages / Q000378:metabolism / Q000528:radiation effects; D009504:Neutrophils / Q000528:radiation effects; D011835:Radiation Protection