The Milk Factor in Blood

Abstract

Whole blood was obtained by heart puncture from 100 mature etherized [female] Paris mice, whose tumor incidence was 92.9 [plus or minus] 1.84% in bred 9 controls. All samples were pooled and the serum was prepared from the pool. Single doses of 0.2 ml. of whole blood or serum, or serum fraction equiv. to 0.2 ml. serum, were inj. subcut. into young [female] C 57 mice which showed no spontaneous mammary carcinoma for 5 yrs. This strain was highly susceptible to the milk factor, developing 76.1 [plus or minus] 4.34% carcinoma of the breast in [female] [female] by foster nursing. The injd. mice were bred and their young were brought up normally under standard control conditions. No tumors appeared in the series treated with whole serum showing there is no hope of using serum for isolation of the agent. All serum fractions gave results consistent with those of whole serum. There was one tumor in 20 mice treated with whole blood. Whole blood and blood fractions are not a rich source of the milk factor.