Destructive Action of Mouse and Rat Tumor Extracts on Red Blood Cells In vitro
Authors: Gross Ludwik 
Published: January 2023

Summary
Centrifugated, or filtered, extracts prepared from mammary carcinomas that developed spontaneously in old female mice were found to possess a hemolytic potency directed specifically against mouse erythrocytes. When 0.5 ml of a tumor extract of 20 per cent concentration was mixed with 1 ml of a 1 per cent suspension of washed mouse erythrocytes, and placed in an incubator at 37 C for 2½ to 3 hours, hemolysis resulted in practically all instances. The red blood cells of rabbits, guinea pigs, chickens and man appear to be resistant to the hemolytic action of the mouse tumor extracts. The hemolytic potency of the tumor extracts prepared from mouse mammary carcinomas was destroyed by heating of the extracts, prior to the tests, to 68 C for 30 minutes. At room temperature (23 C) the centrifugated tumor extracts lose practically all their hemolytic potency after 5 hours. Extracts prepared from mouse mammary carcinomas that had been transplanted for 8 to 60 successive generations, were found to possess in most instances only a weak hemolytic potency; they were occasionally found, however, to clump slightly mouse erythrocytes in vitro. This clumping potency was to a lesser degree, and in some instances only, directed also against erythrocytes of other species of animals. Centrifugated extracts prepared from transplanted rat tumors (a sarcoma and a carcinoma) were found to exert only a weak hemolytic action on rat erythrocytes in vitro; they had, however, a strong hemolytic action on the red blood cells of the mouse. A slight clumping potency of these extracts on rat erythrocytes was also noticed. Extracts prepared from spontaneous mouse leukemia had a hemolytic potency on mouse erythrocytes. In a series of experiments, centrifugated extracts were prepared from various normal organs, such as liver, spleen, lungs, kidneys, muscle, etc., removed from healthy animals of either a high-tumor, a leukemic, or a low-tumor inbred line of mice. Twenty two females, which were either virgins, or did not have any litters for more than 3 months prior to the tests, were used for these experiments. No hemolysis resulted in 59 of the 61 tests. Similar negative results were obtained with extracts prepared from organs removed from 7 healthy males. Hemolysis resulted, however, when extracts prepared from normal mammary glands of nursing, healthy females of either a high-tumor, a leukemic, or a low-tumor line, were mixed with mouse erythrocytes. To a lesser degree this was also observed when mammary tissue extracts were prepared from pregnant female mice. Mouse placenta extracts were also found to possess a moderate hemolytic potency on mouse erythrocytes. Centrifugated extracts prepared from normal liver removed from healthy mice were found to inhibit the hemolytic potency of the tumor extracts, when mixed with the extracts in equal volumes, and incubated at room temperature for 30 minutes prior to the tests. Heating of the liver extracts to 56 C for 30 minutes was found to destroy their inhibiting potency. Extracts prepared from normal mouse kidneys were found to possess a similar, though less constant, inhibiting ability.