HEMATOLOGIC EFFECTS OF RADIATION 



1055 



PANCYTOPENIA INDUCED BY CHRONIC EXPOSURE 

 TO GAMMA RADIATION 



In a series of experiments Lorenz (1951), Lorenz, Jacobson, and Sutton 

 (1950), and Lorenz et al. (1950) studied the hematologic recovery pattern 

 of guinea pigs exposed to 8.8 r (8 hours per day) until an anemia of ca. 2.8 

 million erythrocytes/cu mm had appeared. Leukopenia and thrombo- 

 cytopenia were also invariably present when anemia reached this stage. 

 The dose required to produce an anemia of this magnitude varied from 

 950-1047 r. After removal of the animals from the radiation field, three 

 distinct hematologic recovery patterns were apparent. These three 

 patterns will be designated as groups a, b, and c (Fig. 16-13). 



t/i. 



SI 



o 2 



^■■°-v-°-^- a ''o.^' ■ta.-o'-'S 



J L 



J I L 



J I L 



-20 -10 10 20 30 40 50 60 70 80 90 

 TIME, weeks 



110 



130 



• • CONTROL x x GROUP A, WHICH RECEIVED A TOTAL 



ACCUMULATED DOSE OF I047±275r 

 o -o GROUP B, 9701 130 r o -a GROUP C, 950±59r 



Fig. 16-13. Effect of limited chronic y irradiation at 8.8 r daily (8 hours) on the red- 

 cell count of inbred guinea pigs (family 2). (Lorenz, 1951.) 



Group a. The erythrocyte, hemoglobin, and hematocrit values of the 

 animals with recovery pattern a continued to decrease, and no recovery 

 was apparent, or slight unsustained recovery was observed between six 

 and nine weeks after the animals were removed from the exposure. The 

 platelet values fell no lower after removal of the animals from the radia- 

 tion field and, in fact, rose slowly. The leukocyte values increased 

 rapidly after termination of the exposure. The rise in leukocytes repre- 

 sented a rise in both lymphocytes and heterophils. Contrary to the 

 complete disappearance of reticulocytes following an acute X-ray expo- 

 sure or a 7-ray exposure of this magnitude, no reduction of reticulocytes 

 occurred in these three groups ; in fact, a rapid increase above the control 

 value appeared after termination of the exposure. All animals in group 

 a died within approximately nine weeks after removal from the radiation 

 field. 



Group b. The hematologic findings in the animals with recovery 

 pattern b, during the first nine weeks after termination of the exposure, 

 were approximately the same as the a pattern. After that time the 



