ABSTRACT
Idiotypic immunoglobulin, expressed at the surface of Β lymphoma cells, bears unique clonal sequences which can act as tumor-associated antigens. For two B-cell tumors, BCL1 and A31, arising in different mouse strains, purified idiotypic IgM has been used to immunize animals prior to tumor challenge. In both cases, strong specific protection against tumor was obtained, and anti-idiotypic antibody was identified as a mediator of attack on tumor.
Protected mice were investigated for dormant tumor cells 4-8 months following exposure to tumor; for both lymphomas, the spleens were of normal weight and appearance. However, in the case of the BCL1 tumor, varying numbers of lymphoma cells were identifiable in the spleens by probing with anti-idiotypic antibody. For the A31 tumor, few or no cells could be found by this procedure, but passage of dispersed spleen cells into unimmunized recipients led to development of tumor in 60% of cases. Emergent tumor was indistinguishable from original lymphoma, indicating that cells had been unable to grow in the immune mice, but that this dormant state was disrupted by transfer.
Involvement of Τ lymphocytes, either in helping the anti-idiotypic antibody response, or in attacking tumor directly, has been investigated by isolating and culturing anti-idiotypic Τ cells from immune spleens. Specific cells have been obtained as T-T hybridomas and appear to recognize idiotypic IgM processed by the target Β lymphoma cell.
