Immunobiologic studies in hepatoma-bearing mice passively immunized to alpha-fetoprotein

Mice bearing the BW7756 hepatoma were passively immunized using rabbit antiserum to murine alpha-fetoprotein (AFP) administered in constant or increasing doses. Control tumor-bearing mice were inoculated with saline or nonimmune rabbit serum (NRS) (constant or increasing doses), or were left untreated. The tumor growth curves from mice receiving constant or increasing doses of anti-AFP or constant doses of NRS showed suppression of hepatoma growth; but in both groups of anti-AFP-treated mice this was accompanied by gross anatomical changes, including necrosis, more extensive than in the NRS-treated or other control mice. AFP blood levels roughly paralleled the tumor growth responses. Since an immunological response against the rabbit serum was elicited in the host, it is possible that circulating immune complexes play some role in tumor suppression. Changes observed in liver- and spleen-to-body weight ratios may also reflect a response to circulating immune complexes.