Purification and quantitation of preneoplastic antigen from hyperplastic nodules and normal liver.

The protein in microsomal membranes of hyperplastic nodules of livers from rats fed a diet containing 2-acetyl-aminofluorene referred to as the preneoplastic antigen has been purified to a nearly homogeneous state. A protein sharing identical immunodeterminants based on double agarose diffusion and immunoelectrophoresis has also been detected in deoxycholate-solubilized microsomes from normal liver, but it cannot be detected by gel immunodiffusion in the absence of detergent. There is approximately 4 times as much of this antigen in hyperplastic nodule microsomes as there is in normal microsomes as determined by electroimmunoassay. The antigen from nodules is not more than one-half the molecular weight of the antigen derived from normal microsomes in 0.2% deoxycholate. These findings are consistent with the hypothesis that an altered state of membranes exists in hyperplastic nodule endoplasmic reticulum, resulting in increased amounts of immunoreactive preneoplastic antigen. The nodule protein has a decreased association with its membrane matrix.