Spontaneous reticulum cell sarcoma in SJL/J mice has been proposed as an animal tumor model for Hodgkin's lymphoma. The relationship of tumor progression and immune function is not clear, however, and has prompted a systematic evaluation of SJL/J immune competence. It was found that the ability to generate cell-mediated immunity and antibody response to allografts was not impaired in 2-to 12-month-old mice, regardless of their tumor status. All animals were capable of generating in vivo cytotoxic effector T-cells and both IgG and IgM classes of cytotoxic antibody to a tumor allograft. In addition to being able to respond, older mice showed an unexpected hyperresponsiveness to alloantigens, which suggested that escape from feedback control might be a characteristic of SJL/J mice. Loss of immune regulation was further indicated by the failure to induce tolerance to human γ-globulin in mice 4 months and older, while 3-week-old SJL/J mice could be rendered unresponsive. Coincident with this apparent loss of regulation, circulating antibodies to synthetic doublestranded RNA, polyinosinic · polycytidylic acid, were first detected in unimmunized mice at 4 months of age, and titers remained elevated regardless of tumor status. It is suggested that tumor development as well as autoimmunity may result from an effective amplification of the immune response.
This work was supported by Grant CA 12800 from the National Cancer Institute, NIH, Bethesda, Md., and by a Grant from the California Institute of Cancer Research.