Humoral and cellular immune responses to mouse mammary tumor virus (MMTV) in experimental animal models (review).

Mouse mammary tumor virus (MMTV) has been implicated in the etiology of mouse mammary tumors although genetic, hormonal and environmental factors appear to be involved in the mechanism of carcinogenesis. Strains from mice harboring the exogenous MMTV have higher incidences of spontaneous mammary tumors than those who are devoid of the B type particles. However, multiple copies of MMTV provirus are detectable in all inbred strains of mice regardless of whether they develop spontaneous tumors or not. Studies by several investigators have demonstrated humoral and cell mediated immune responses in mice which harbor the endogenous virus and in strains that possess the exogenous MMTV in addition to the provirus. These immune responses are in some cases modulated by the development of mammary tumors. In analogy with the results in mice, there have been several studies where human breast cancer patients have shown responses to mouse mammary tumor virus antigens. Furthermore, MMTV related sequences have been detected in DNA from human cells. The animal systems therefore, appear to be valid models for the understanding of human mammary carcinogenesis and to establish protocols for its eventual control.