In Vitro Studies on the Anemia of Tumor-Bearing

T HE POSSIBILITY that the anemia in some cancer patients was due to the hemolytic effect of toxins produced by the tumor was first analyzed by Weil2#{176}in 1908. He demonstrated that extracts of normal human and animal organs had a lytic effect in vitro on red blood cells although there was con-siderable variability in the hemolytic potency of these extracts. Moreover, he reported that both necrotic and non-necrotic tumors had some hemolytic effect, with more hemolysis produced by the necrotic tumors. Weil concluded from these studies that the anemias associated with malignant tumors were probably due in part to the direct hemolytic action of products of necrosis in the tumor. Gross7#{176} reported that heniolysis of the donor’s red blood cells could be produced in vitro by a saline-extracted, filtrable, thermolabile substance derived tinder aseptic conditions from mouse and human neoplasms. He extracted his lytic material from tumors which were primarily composed of viable-appearing tumor tissue. There was no separation of the extracts ob