Effect of anti-alpha1-fetoprotein on alpha1-fetoprotein-producing rat tumors in vivo and in vitro.

Active or passive immunization of rats to alpha1-fetoprotein (AFP) does not consistently inhibit the growth of AFP-producing transplantable hepatomas in vivo, and anti-AFP does not kill these hepatomas in vitro. However, 3 of 14 rats in 1 experiment responded to passive immunization by reversal of tumor growth as evidenced by normalization of elevated AFP serum concentrations, and 1 of 9 rats actively immunized with rat AFP in complete Freund's adjuvant had suppressed growth of transplantable hepatoma 7777.