Changes in the Phagocytic Activity of Polyrnorphonuclear Leukocytes following Total Body X-Irradiation

By \I. WILKINSON W HILE X-IRRADIATION ins sufficienst. dosage will depress the number of circulating leukocytes, little is kmsowns about its effect oms the functions of those few leukocytes which constimsue to be formed amid delivered to the blood stream. Durimsg histologic studies ons the lymph msodes of rabbits exposed to 600 r or 800 r x-irradiatiots and sacrificed at instervals up to twensty-four hours after irradiations, Bloom’ ,soticed that while some areas of cellular debris were imifiltrated with polymorphomsuclear leukocytes, these cells showed mso evidence of phagocytic activity. Gletsn2 ‘ studied the phagocytic insdices (i.e., the average msumber of bacteria imigested per leukocyte) of rabbits followinsg x-irradiatiots of varying dosage arid quality. Following ans optimal dose of 350 r (measured ins air) delivered at 140 kv. to a small area of skiti, the phagocytic itsdex for Staphylococcus aureus showed a definite rise, maximal after forty-eight. hours atsd subsidimsg to tsormal sevens days after the irradiations. Esplin, et al.,4 usinsg an irs vivo techtsic, studied the phagocytic al)ihty of mouse leukocytes for Micrococcus pyogenes at two amid six days followiisg 350 r total body x-irradiatioms. At both times, the leukocytes from the irradiated ansimals constainsed more bacteria thams (lid those from nsormal ansimals, hut this may have beets partly or wholly due to the leukopemsia its the former group. Usitsg mixtures of leukocytes amid bacteria, it has beets shownsm that if the conscenstrations of bacteria is kept cotsstarst, a fall ins the numbers of leukocytes will cause ans inscrease its the percetstage of active phagocytes, amid in the average tsumber of l)acteria per leukocyte, though the total amoumit of phagocytosis ins the system will i)e decreased. This is probably due to the greater isumber of bacteria available to each phagocyte its the case of the leukopemsic mixture. Its the presemst. itsvestigations, using a modificatioms of the t.echmsique recommemsded by Boermser amid Mudd,6 the its vitro phagocytic activity of leukocytes from irradiated rats w’as studied over a period of two weeks. A prehimi sary study ots mice showed a defitsite decrease ims phagocytosis from the sixth day to the termimsatioms of the experiment ons the twelfth day followinsg 350 r x-irradiatioms. Ow’ing to severe leukopetsia, it w-as impossible to make adeqrmate counts bef ore the sixth day. The following experimemst. was thems plamsnsed to confirm this finding, and by doing parallel phagocytic studies oms suspenssionss of nsormal