Detection of rare cells expressing shared lymphoma idiotypes in fetal spleens

Monoclonal antibodies have been derived against the shared and private idiotypes of immunoglobulin expressed by human B-cell lymphomas. We performed indirect immunofluorescence assays on cells from 3 fetal spleens, 3 adult spleens and 10 hyperplastic lymph nodes with a panel of 5 monoclonal antibodies directed to private lymphoma idiotypes, 2 antibodies directed to shared lymphoma idiotypes and various positive and negative control antibodies. Rare (less than 5%) cells in the fetal spleens, adult spleens and hyperplastic lymph nodes reacted with the 2 antibodies directed to shared lymphoma idiotypes. No cells in any of the specimens were reactive with the antibodies directed to private lymphoma idiotypes. We conclude that rare cells expressing shared lymphoma idiotypes are present during fetal development and in mature lymphoid tissue. This suggests that shared lymphoma idiotypes are expressed as part of a developmental process rather than in response to a specific environmental antigen.