BIOLOGY AND MEDICINE
The principal conclusions of the conference were that: (1) mutation rates recorded at
Harwell and at Oak Ridge were in agreement as far as the studies went, and (2) studies at
exposures between 37.5 and 300 roentgens are needed to bridge the gap between the Harwell
- and Oak Ridge studies. A similar conference at the Oak Ridge National Laboratory ig planned
for the summerof 1958, following the Genetics Congress in Montreal.
STATUS OF TREATMENT OR IRRADIATION INJURY
DOE ARCHIVES
The possibility has recently developed that a more effective treatment can be worked out
for persons exposed to doses of radiation in the 200- to 600-roentgen range.
When it was found that irradiated mice could be saved by the introduction of material
from the spleen or bone marrow,it was first believed that simple extractives or perhaps pure
chemical substances could be found that would modify the lethal course of the radiation
syndrome. This idea has not been completely abandoned, but emphasis has shifted to trans-
plantation of the progenitors of the cellular elements of the blood which will grow in the irradiated animal and tide him over the period when the functioning of his own bone marrow is
depressed.
Severe depression amounting to failure of blood formation in the bone marrow is re-
sponsible for most of the deaths which occur in animals some 7 to 30 days after exposure.
Ordinarily, tissues transplanted from one individual to another of the same but not inbred
strain, and even more definitely to another individual of a different strain or species, are
rejected and destroyed by the recipient. In the animal which has been given a lethal dose of
radiation, however, this immunereaction is more or less lost, so that transplants of bone
marrow becomea novel possibility with practical applications in man.
Experimental work has shown that the irradiated animal will accept bone marrow transplants from different strains and species, but the transplant becomes increasingly less successful the greater the phylogenetic difference between the donor and the recipient. Thus, it is
found that the irradiated mouse will readily accept marrow from all other mice, but the trans-
plant of rat marrow is less certain, and dog or human marrow apparently fails to take permanently, Conversely, the greater the genetic similarity between the donor and the recipient, the
. dower the dose of radiation needed for a successful bone marrow transplant. Prior to this
discovery concerning the effects of radiation on transplanta, it was the generally accepted
belief that transplants in man are possible only between identical tissues.
“These marrow transplants are not merely stopgaps, for it has been shown in a numberof
ways that the transplanted cells continue to live and function in the recipient. For example,
some irradiated mice which have received rat bone marrow have recovered from the radiation syndrome and then continueto live out their life span, but with circulating blood cells
which wereall definitely those of the rat; in some instances the mouse’s own marrow will
recover sufficiently to suppress the rat cells completely; in others the mousewill have circulating blood cells of both species.
Problems in methods of securing, handling, storing, and preserving marrow are largely
technical, and their satisfactory solution can be anticipated with a fair degree of confidence.
On the other hand,it is evident from these new findings that knowledge of immunology and the
general field of tissue transplantation is deficient.
Knowledge concerning the immune relationships between lower animals is of definite value
in establishing the patterns to be studied and explored in developing a practical clinical application of marrow transplantation. Idiotransplants are presently feasible; such a transplant
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