It seemed desirable to investigate further the possible role of complement and its components in the protective action of serum against transplanted neoplasms. It is the purpose of this thesis to present data which suggest that the C'4 component plays an active part in this process though the mechanism is not disclosed.

A model for the study of the relationship of immunity to cancer is found in AKR mice which harbor Gross virus. This genetically transmitted virus is present in a latent form for months before it spontaneously induces leukemia. Many investigators have demonstrated near normal humoral responses, but abnormal cellular immunity in the preleukemic animal. With increasing age, pathology of the disease is expressed, reflecting diminished immunity. In this study, the ontogeny of humoral antibodies of AKR/J and SWR/J mice was assayed by microagglutination techniques in response to thymus-independent, thymus-dependent, and solubilized antigens. Simultaneous injections of thymusdependent and -independent antigens provided data suggesting an impaired humoral response in the AKR mouse.

This thesis has been an attempt to observe the role antibodies play in extending the life span of tumor infected Akr mice.

The AKR strain of mice have a genetic trait for spontaneous development of lymphocytic leukemia. In this study, leukemic mice were found to have significantly larger (p<0.01) thymuses and spleens than preleukemic mice. The enlarged leukemic tissues were densely packed with a light staining cell, with a hollow-appearing nucleus. Tissues from preleukemic mice were observed to be infiltrated with a smaller, darker-staining lymphocyte. Fluorescent antibody staining was done on preleukemic and leukemic tissues, using three antisera against murine lymphocyte theta antigen, and an antiserum against murine IgG. Significantly brighter fluorescence, (p <0.05) with theta-specific antisera, was found in leukemic thymuses,spleens, and kidneys than in the same preleukemic tissues. Leukemic tissues had significantly brighter fluorescence (p <0.05) than preleukemic tissues with IgG antiserum.