Leukaemias in BN/a and BN/b mice after prolonged treatment with antilymphocyte globulin.

The influence of prolonged treatment with antilymphocyte globulin on tumour incidence in BN/a and BN/b mice was studied. One ALG sample appeared to be highly leukaemogenic in two independent experiments. All treated mice developed, after a short latency period, non-thymic lymphomas with involvement of abdominal lymph nodes and spleen resulting in ascites. Three established ascites leukaemia cell lines were examined for the presence of MuLV. In all lines viral C-type particles, soluble viral gs-1 antigen and cell surface antigen related to Gross virus were demonstrated. The mechanism of induction of these tumours remains obscure. Thy hypothetical role of immunosuppression, stimulation of lymphoid cells and activation of leukaemogenic virus is discussed.