Host response to tumor-associated fetal antigens: kinetics and components

Using a colony-inhibition bioassay that measures the contribution of the host response in transplantation immunity to tumor-associated fetal antigens (TAFA), I evaluated the occurrence of TAFA during different developmental stages of murine fetal liver cells. A maximum concentration of TAFA was present at approximately 15 days' gestation. A similar age-equivalence phase of gestation was also found in pig fetal liver. Host-response kinetics to TAFA were examined, and results indicated a similar pattern of activity for tumor- or fetal-immunized groups with a transient immune suppression in the middle of the study period. I detected specific antibodies generated by tumor and fetal cell immunization by a complement-dependent serum microcytotoxicity assay. The specificity of the reaction was evaluated further by absorption studies that demonstrated specific cross-reactive antibodies to fetal and tumor cell targets. Adoptive transplanted immunity to TAFA was indirectly evaluated by a modified Winn assay which indicated that a cellular immune mechanism was an important component of the host response to TAFA.