Immune responses in preleukaemic and leukaemic AKR mice

The proliferation of haemolytic plaque‐forming cells in the spleen of preleukaemic AKR mice following primary immunization with sheep red cells was slightly delayed and the peak response was not as high as in normal mice. In leukaemic AKR mice, although there were normal numbers of background plaque‐forming cells in the spleens of unimmunized animals, these cells failed to proliferate following antigenic stimulation and no detectable haemolysin antibody response occurred before the seventh day following immunization. Haemagglutinin responses were normal in preleukaemic AKR mice but were depressed severely in mice with thymic lymphomata or generalized lymphoid leukaemia. The present results do not support the concept that severe immunological deficiencies are a necessary prerequisite of the preleukaemic state.