Effect of immune manipulation on natural immune responses to murine mammary tumor antigens.

The virus-host relationship in BALB/cfC3H virgin female mice neonatally infected with an oncogenic virus (mammary tumor virus) (MuMTV) was significantly altered by a brief immunosuppressive treatment during young adult life. Natural immune responses were augmented and changed. The ability of lymphoid cells to attack target cells expressing MuMTV-associated antigens was significantly increased, and a new component, a non-T-cell reactivity, was added to the T-cell reactivity found in normal females. Serum blocking factors were both quantitatively and qualitatively altered.