Effect of a Transplanted Plasma-Cell Tumor on Antibody Formation

Abstract

Circulating antibody content after a single injection of sheep erythrocytes was observed in C3H/Lw mice bearing the plasma-cell tumor X5563. Hemolysin titers were within control limits for all mice tested whose tumors represented less than 5 percent of their body weight when they were killed. Among some mice, with tumors that weighed from about 5 to 30 percent of body weight, serum antibody content was lower with increased tumor weight, while in other mice bearing comparable tumors no serum hemolysin was detected even with a sensitive colorimetric procedure. The possibility of an increased rate of disappearance of autologous antibody was suggested by the sharp drop in serum hemolysin content at 5 to 7 days after antigen injection compared to that in controls, and from the observation in other experiments that passively transferred homologous antibody disappeared at a faster rate in tumor-bearing mice than in their controls. In addition, average blood volume in the tumor-bearing mice of one experiment was over 30 percent greater than in control mice of equal size and age. Hypervolemia would represent a dilution of the antibody if the primary response was equal and maximal in both tumor-bearing mice and their controls. Hemolysin titers were near control values in mice singly immunized after X-ray-induced regression of their plasma-cell tumors. A substantial secondary immune response was recorded in all mice tested with more than one injection of sheep erythrocytes or soluble antigens. These results suggest that the observed lowered antibody titers in the tumors-bearing mice after primary immunization may have been partly attributable to a reduction in the number of antibody-producing cells participating in the primary response.