Environment-Breast Cancer Link and Community Outreach Targeted

THE ROLE of the immune system during oncogenesis by mouse mammary-tumour virus (MTV) is yet to be completely elucidated. Humoral (Blair et al., 1966; Hilgers et al., 1971; lhle et al., 1976) and cellular (Blair, 1976; Creemers & Bentvelzen, 1977; Sigel et al., 1976; Stutman, 1976; Tagliabue et al., 1978) immunity against MTV antigens is expressed by MTVinfected mice relatively early in their life. However, since it has been established that immunosuppressive treatments such as neonatal thymectomy (Martinez, 1964; Heppner et al., 1968) or injections with antilymphocyte sera (Lappe & Blair, 1970) reduce the incidence and delay the appearance of mammary tumours in MTV-bearing hosts, a possible enhancing role for the immune system on tumour growth has been suggested for MTV tumorigenesis (Prehn & Lappe, 1971). In an attempt to provide a better understanding of the interactions between immune responses and MTV infections, we evaluated several in vitro immune parameters (Tagliabue et al., 1980) of virgin C3H/HeN (C3H) female mice infected with MTV for comparison with genetically identical C3H/HeN (C3Hf) mice freed of MTV by foster-nursing. It was found that C3H mice 14-20 weeks of age have cellmediated immunity against MTV antigens, measured as lymphokine production. By contrast, this reactivity is never detectable in younger or older C3H mice or in Accepte(d 7 Alay 1981