Antibody-Mediated Hemadsorption by Tumor Tissues

Abstract

Sarcoma induced by methylcholanthrene and maintained by transplantation in C3H mice was used throughout this study. It was demonstrated that cryostat sections or cell cultures of the tumor would adsorb sheep erythrocytes in the presence of anti-sheep-erythrocyte antibodies. The hemadsorption test could be performed by adding unsensitized erythrocytes to tumor sections or cultures previously treated with the antiserum (pro cedure 1) or alternatively by adding antibody-sensitized erythrocytes to untreated tumor sections or cultures (procedure 2). Procedure 1 was less sensitive and required 2 to 4 times higher antibody concentrations than procedure 2. Anti-sheep erythrocyte antibodies of rabbits, man, mouse and guinea pig were capable of mediating hemadsorption. Apparently, Ig.G but not IgM antibodies were active. The following evidence was presented in favor of the hypothesis that the hemadsorption is mediated by cytophilic-like antibodies with affinity to tumor cells: Hemadsorption was inhibited by Fraction II of normal human or rabbit sera. Covering of Fc fragment of antibodies on sensitized erythrocytes by horse complement interfered with hemadsorption. 5S fragments of rabbit anti-sheep erythrocyte antibodies failed to mediate hemadsorption. At least some of the observed phenomena were due to antibodies directed against similar or identical antigenic sites on tumor cells and sheep erythrocytes. Such antibodies might have served as bridges connecting these 2 types of cells.