Early detection of tumor-specific antibodies to mammary carcinoma.

BALB/cfC3H female mice which develop mammary tumor virus (MTV)-induced mammary tumors possess not only serun antibodies directed against virus-associated antigens which are expressed on mammary tumor cells but also antibodies directed against antigenic specificities which are unique to each tumor. The possible range of unique specificities is considerable; a survey of serum samples from 18 tumor-bearing females revealed only two which reacted with a tumor-unique specificity of another isologous MTV-induced mammary tumor. A retrospective study revealed that in multiparous females, the serum activity against tumor-unique antigenicity could be detected 1 to 4 months before the tumor was grossly visible. On the other hand, in virgin females, the serum activity was detectable only when the tumor was visible. On the basis of this difference in time of origin of reactivity, we speculate that the mechanism of tumor formation in parous females may involve a longer preneoplastic or latent neoplastic period than in virgin females; in the latter the change from normal to overtly neoplastic appears to be more abrupt.