TRANSMISSIBLE FOWL LEUKOSIS 25 



The activity of the crude extract was about the same as that of the high-speed 

 centrifugate. The centrifugate of crude tumor extract containing approximately 

 10-5 nig. nitrogen produced tumors at the site of injection in chicks. A 

 carbohydrate-splitting enzyme preparation reduced the viscosity of crude tumor 

 extracts, but had no efTect in increasing the activity of the extract. 



Centrifugate from 10 cc. serum of a normal chick contained 0.34 mg. nitrogen, 

 although this value varied somewhat in specimens taken from the same chicks 

 at different times. About twice the normal amount of sedimentable material was 

 obtained from serum of a chicken affected with Strain 1 leukosis, and the average 

 amount of serum centrifugate in cases of leukosis produced by Strain 13 was 

 only slightly higher than that from normal serum. Normal chicken and mouse 

 spleens and other human and mouse tissues examined contained large amounts of 

 material sedimentable by high-speed centrifugation. It was thus indicated that 

 the mere presence or am.ount of centrifugate had no relation to the disease- 

 producing agent. The centrifugate of leukotic plasma or leukotic cell washings 

 (the leukosis being produced by either the Strain 1 or Strain 13 agent) was capable 

 of producing the disease. The centrifuged deposit of the second washing of 

 leukotic cells was feeble in this power, as only two of eleven birds so inoculated 

 with 1 :5 dilution became affected with leukosis. The washed leukotic cells were 

 much more active in producing leukosis, and irradiation with 15,000 r of roentgen 

 rays did not significantly reduce this ability, although the cells themselves were 

 destroyed. 



The centrifugate of tumor e.xtracts maintained its activity for six months at 

 — 60° C, but deteriorated rapidly at ice-box temperature. This deterioration 

 was slightly slowed by the addition of 5 percent of a saturated solution of sodium 

 sulfate or magnesium sulfate. Gum acacia, tumor polysaccharide or supernatant 

 fluid were devoid of such effect. The sedimentable fraction of tumor extract could 

 also be precipitated by one-third saturation of the extract with sodium sulfate. 



Morelli and Vercellone (141 b) observed that plasma in the atypical anemic 

 forms of erythroblastic leukosis produced by the Oberling and Guerin agent was 

 much less active than whole blood. These workers had found (141 a) that addition 

 of ascorbic acid (in 1 :200 concentration) to leukotic plasma produced a precipitate 

 and after its removal the treated plasma was more active in producing disease. 

 They (141 b) used this ascorbic acid treatment coupled with absorptions by a 

 modified Willstatter's type C aluminum hydroxide in attempts to purify the 

 leukotic agent. They were able to produce disease with plasma from atypical 

 anemic erythroblastic leukosis that had been subjected to treatment with either 

 ascorbic acid alone or a combination of ascorbic acid and alurhinum hydroxide. 

 It was found that after repeated absorptions with aluminum hydroxide had 

 reduced the nitrogen content of the treated plasma to less than 10 percent of the 

 original value, the activity was lost. Attempts to reactivate such inactive plasma 

 by addition of hemoglobin or normal plasma gave xariable results which were not 

 considered sufficiently clear to settle the question. 



Ruffilli (174 k) reports that the plasma of a chicken which subsequently re- 

 covered from leukosis was not infective during the period of the disease. The 

 plasma was, however, capable of producing disease after being reduced by the 

 action of cystein. The whole blood of this chicken produced leukosis without 

 treatment. 



Lee and Wilcke (124) have reported that the isoelectric point of the agent in a 

 filtrate of the affected ovary from a bird with "the lymphoid type of fowl leuko- 

 sis" was between the pH values of 6.01 and 7.01. Although erythroblastic and 

 granuloblastic leukosis occurred in the birds inoculated with this material there 



