Defining the heterogeneity of anti-tumor antibody responses

Studies were undertaken to analyze the humoral in vivo and in vitro antibody response of BALB/c mice to a syngeneic MSV-induced tumor cell line. With a sensitive radioimmunoassay, sera obtained from individual progressor and regressor mice were shown to vary greatly in total tumor-specific antibody concentration as well as immunoglobulin class distribution of the antibody, but no significant difference existed between the groups of progressor and regressor mice as a whole. In addition, serum antibodies from all animals were shown to have extensive cross-reactivity against a variety of cell lines chosen to share one or more antigens with the cell line used for immunization. Conversely, when in vitro fragment cultures of splenic tissue from progressor and regressor mice were stimulated with tumor-related antigen, differences in responsiveness among normal, progressor, and regressor mice were observed. In addition, antibodies derived from fragment cultures displayed several different cross-reactivity patterns all of which were more restricted in specificity than serum antibodies.